diff --git a/contrib/zmq/zmq_sub.py b/contrib/zmq/zmq_sub.py
index 103556cbd..aed948265 100755
--- a/contrib/zmq/zmq_sub.py
+++ b/contrib/zmq/zmq_sub.py
@@ -1,87 +1,88 @@
 #!/usr/bin/env python3
 # Copyright (c) 2014-2017 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 """
     ZMQ example using python3's asyncio
 
     Bitcoin should be started with the command line arguments:
         bitcoind -testnet -daemon \
                 -zmqpubrawtx=tcp://127.0.0.1:28332 \
                 -zmqpubrawblock=tcp://127.0.0.1:28332 \
                 -zmqpubhashtx=tcp://127.0.0.1:28332 \
                 -zmqpubhashblock=tcp://127.0.0.1:28332
 
     We use the asyncio library here.  `self.handle()` installs itself as a
     future at the end of the function.  Since it never returns with the event
     loop having an empty stack of futures, this creates an infinite loop.  An
     alternative is to wrap the contents of `handle` inside `while True`.
 
     A blocking example using python 2.7 can be obtained from the git history:
     https://github.com/bitcoin/bitcoin/blob/37a7fe9e440b83e2364d5498931253937abe9294/contrib/zmq/zmq_sub.py
 """
 
 import binascii
 import asyncio
 import zmq
 import zmq.asyncio
 import signal
 import struct
 import sys
 
 if not (sys.version_info.major >= 3 and sys.version_info.minor >= 5):
     print("This example only works with Python 3.5 and greater")
     sys.exit(1)
 
 port = 28332
 ip = "172.31.9.161"
 
 
 class ZMQHandler():
     def __init__(self):
         self.loop = asyncio.get_event_loop()
         self.zmqContext = zmq.asyncio.Context()
 
         self.zmqSubSocket = self.zmqContext.socket(zmq.SUB)
+        self.zmqSubSocket.setsockopt(zmq.RCVHWM, 0)
         self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashblock")
         self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "hashtx")
         self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawblock")
         self.zmqSubSocket.setsockopt_string(zmq.SUBSCRIBE, "rawtx")
         self.zmqSubSocket.connect(f"tcp://{ip}:{port}")
 
     async def handle(self):
         msg = await self.zmqSubSocket.recv_multipart()
         topic = msg[0]
         body = msg[1]
         sequence = "Unknown"
         if len(msg[-1]) == 4:
             msgSequence = struct.unpack('<I', msg[-1])[-1]
             sequence = str(msgSequence)
         if topic == b"hashblock":
             print(f'- HASH BLOCK ({sequence}) -')
             print(binascii.hexlify(body))
         elif topic == b"hashtx":
             print(f'- HASH TX  ({sequence}) -')
             print(binascii.hexlify(body))
         elif topic == b"rawblock":
             print(f'- RAW BLOCK HEADER ({sequence}) -')
             print(binascii.hexlify(body[:80]))
         elif topic == b"rawtx":
             print(f'- RAW TX ({sequence}) -')
             print(binascii.hexlify(body))
         # schedule ourselves to receive the next message
         asyncio.ensure_future(self.handle())
 
     def start(self):
         self.loop.add_signal_handler(signal.SIGINT, self.stop)
         self.loop.create_task(self.handle())
         self.loop.run_forever()
 
     def stop(self):
         self.loop.stop()
         self.zmqContext.destroy()
 
 
 daemon = ZMQHandler()
 daemon.start()
diff --git a/doc/zmq.md b/doc/zmq.md
index ba1263642..3d4d22a75 100644
--- a/doc/zmq.md
+++ b/doc/zmq.md
@@ -1,107 +1,118 @@
 # Block and Transaction Broadcasting with ZeroMQ
 
 [ZeroMQ](http://zeromq.org/) is a lightweight wrapper around TCP
 connections, inter-process communication, and shared-memory,
 providing various message-oriented semantics such as publish/subscribe,
 request/reply, and push/pull.
 
 The Bitcoin ABC daemon can be configured to act as a trusted "border
 router", implementing the bitcoin wire protocol and relay, making
 consensus decisions, maintaining the local blockchain database,
 broadcasting locally generated transactions into the network, and
 providing a queryable RPC interface to interact on a polled basis for
 requesting blockchain related data. However, there exists only a
 limited service to notify external software of events like the arrival
 of new blocks or transactions.
 
 The ZeroMQ facility implements a notification interface through a set
 of specific notifiers. Currently there are notifiers that publish
 blocks and transactions. This read-only facility requires only the
 connection of a corresponding ZeroMQ subscriber port in receiving
 software; it is not authenticated nor is there any two-way protocol
 involvement. Therefore, subscribers should validate the received data
 since it may be out of date, incomplete or even invalid.
 
 ZeroMQ sockets are self-connecting and self-healing; that is,
 connections made between two endpoints will be automatically restored
 after an outage, and either end may be freely started or stopped in
 any order.
 
 Because ZeroMQ is message oriented, subscribers receive transactions
 and blocks all-at-once and do not need to implement any sort of
 buffering or reassembly.
 
 ## Prerequisites
 
 The ZeroMQ feature in Bitcoin ABC requires the ZeroMQ API >= 4.1.5
 [libzmq](https://github.com/zeromq/libzmq/releases).
 For version information, see [dependencies.md](dependencies.md).
 Typically, it is packaged by distributions as something like
 *libzmq3-dev*. The C++ wrapper for ZeroMQ is *not* needed.
 
 In order to run the example Python client scripts in contrib/ one must
 also install *python3-zmq*, though this is not necessary for daemon
 operation.
 
 ## Enabling
 
 By default, the ZeroMQ feature is automatically compiled.
 To disable, use -DBUILD_BITCOIN_ZMQ=OFF to `cmake` when building bitcoind:
 
     $ cmake -GNinja .. -DBUILD_BITCOIN_ZMQ=OFF [...]
 
 To actually enable operation, one must set the appropriate options on
 the command line or in the configuration file.
 
 ## Usage
 
 Currently, the following notifications are supported:
 
     -zmqpubhashtx=address
     -zmqpubhashblock=address
     -zmqpubrawblock=address
     -zmqpubrawtx=address
 
 The socket type is PUB and the address must be a valid ZeroMQ socket
 address. The same address can be used in more than one notification.
 
+The option to set the PUB socket's outbound message high water mark
+(SNDHWM) may be set individually for each notification:
+
+    -zmqpubhashtxhwm=n
+    -zmqpubhashblockhwm=n
+    -zmqpubrawblockhwm=n
+    -zmqpubrawtxhwm=n
+
+The high water mark value must be an integer greater than or equal to 0.
+
 For instance:
 
     $ bitcoind -zmqpubhashtx=tcp://127.0.0.1:28332 \
-               -zmqpubrawtx=ipc:///tmp/bitcoind.tx.raw
+               -zmqpubrawtx=ipc:///tmp/bitcoind.tx.raw \
+               -zmqpubhashtxhwm=10000
 
 Each PUB notification has a topic and body, where the header
 corresponds to the notification type. For instance, for the
 notification `-zmqpubhashtx` the topic is `hashtx` (no null
 terminator) and the body is the transaction hash (32
 bytes).
 
 These options can also be provided in bitcoin.conf.
 
 ZeroMQ endpoint specifiers for TCP (and others) are documented in the
 [ZeroMQ API](http://api.zeromq.org/4-0:_start).
 
 Client side, then, the ZeroMQ subscriber socket must have the
 ZMQ_SUBSCRIBE option set to one or either of these prefixes (for
 instance, just `hash`); without doing so will result in no messages
 arriving. Please see `contrib/zmq/zmq_sub.py` for a working example.
 
 ## Remarks
 
 From the perspective of bitcoind, the ZeroMQ socket is write-only; PUB
 sockets don't even have a read function. Thus, there is no state
 introduced into bitcoind directly. Furthermore, no information is
 broadcast that wasn't already received from the public P2P network.
 
 No authentication or authorization is done on connecting clients; it
 is assumed that the ZeroMQ port is exposed only to trusted entities,
 using other means such as firewalling.
 
 Note that when the block chain tip changes, a reorganisation may occur
 and just the tip will be notified. It is up to the subscriber to
 retrieve the chain from the last known block to the new tip.
 
 There are several possibilities that ZMQ notification can get lost
 during transmission depending on the communication type you are
 using. Bitcoind appends an up-counting sequence number to each
 notification which allows listeners to detect lost notifications.
diff --git a/src/init.cpp b/src/init.cpp
index bcc6927e3..40b202d8f 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -1,2780 +1,2805 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #if defined(HAVE_CONFIG_H)
 #include <config/bitcoin-config.h>
 #endif
 
 #include <init.h>
 
 #include <addrman.h>
 #include <amount.h>
 #include <avalanche.h>
 #include <banman.h>
 #include <blockfilter.h>
 #include <chain.h>
 #include <chainparams.h>
 #include <checkpoints.h>
 #include <compat/sanity.h>
 #include <config.h>
 #include <consensus/validation.h>
 #include <flatfile.h>
 #include <fs.h>
 #include <httprpc.h>
 #include <httpserver.h>
 #include <index/blockfilterindex.h>
 #include <index/txindex.h>
 #include <interfaces/chain.h>
 #include <key.h>
 #include <miner.h>
 #include <net.h>
 #include <net_permissions.h>
 #include <net_processing.h>
 #include <netbase.h>
 #include <node/context.h>
 #include <policy/mempool.h>
 #include <policy/policy.h>
 #include <policy/settings.h>
 #include <rpc/blockchain.h>
 #include <rpc/register.h>
 #include <rpc/server.h>
 #include <rpc/util.h>
 #include <scheduler.h>
 #include <script/scriptcache.h>
 #include <script/sigcache.h>
 #include <script/standard.h>
 #include <shutdown.h>
 #include <timedata.h>
 #include <torcontrol.h>
 #include <txdb.h>
 #include <txmempool.h>
 #include <ui_interface.h>
 #include <util/moneystr.h>
 #include <util/system.h>
 #include <util/threadnames.h>
 #include <util/translation.h>
 #include <util/validation.h>
 #include <validation.h>
 #include <validationinterface.h>
 #include <walletinitinterface.h>
 
 #include <boost/algorithm/string/classification.hpp>
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/split.hpp>
 #include <boost/thread.hpp>
 
 #if ENABLE_ZMQ
+#include <zmq/zmqabstractnotifier.h>
 #include <zmq/zmqnotificationinterface.h>
 #include <zmq/zmqrpc.h>
 #endif
 
 #ifndef WIN32
 #include <attributes.h>
 #include <cerrno>
 #include <csignal>
 #include <sys/stat.h>
 #endif
 #include <cstdint>
 #include <cstdio>
 #include <memory>
 
 static const bool DEFAULT_PROXYRANDOMIZE = true;
 static const bool DEFAULT_REST_ENABLE = false;
 static const bool DEFAULT_STOPAFTERBLOCKIMPORT = false;
 
 // Dump addresses to banlist.dat every 15 minutes (900s)
 static constexpr int DUMP_BANS_INTERVAL = 60 * 15;
 
 #ifdef WIN32
 // Win32 LevelDB doesn't use filedescriptors, and the ones used for accessing
 // block files don't count towards the fd_set size limit anyway.
 #define MIN_CORE_FILEDESCRIPTORS 0
 #else
 #define MIN_CORE_FILEDESCRIPTORS 150
 #endif
 
 /**
  * The PID file facilities.
  */
 static const char *BITCOIN_PID_FILENAME = "bitcoind.pid";
 
 static fs::path GetPidFile() {
     return AbsPathForConfigVal(
         fs::path(gArgs.GetArg("-pid", BITCOIN_PID_FILENAME)));
 }
 
 NODISCARD static bool CreatePidFile() {
     fsbridge::ofstream file{GetPidFile()};
     if (file) {
 #ifdef WIN32
         tfm::format(file, "%d\n", GetCurrentProcessId());
 #else
         tfm::format(file, "%d\n", getpid());
 #endif
         return true;
     } else {
         return InitError(
             strprintf(_("Unable to create the PID file '%s': %s").translated,
                       GetPidFile().string(), std::strerror(errno)));
     }
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //
 // Shutdown
 //
 
 //
 // Thread management and startup/shutdown:
 //
 // The network-processing threads are all part of a thread group created by
 // AppInit() or the Qt main() function.
 //
 // A clean exit happens when StartShutdown() or the SIGTERM signal handler sets
 // ShutdownRequested(), which triggers the DetectShutdownThread(), which
 // interrupts the main thread group. DetectShutdownThread() then exits, which
 // causes AppInit() to continue (it .joins the shutdown thread). Shutdown() is
 // then called to clean up database connections, and stop other threads that
 // should only be stopped after the main network-processing threads have exited.
 //
 // Shutdown for Qt is very similar, only it uses a QTimer to detect
 // ShutdownRequested() getting set, and then does the normal Qt shutdown thing.
 //
 
 /**
  * This is a minimally invasive approach to shutdown on LevelDB read errors from
  * the chainstate, while keeping user interface out of the common library, which
  * is shared between bitcoind, and bitcoin-qt and non-server tools.
  */
 class CCoinsViewErrorCatcher final : public CCoinsViewBacked {
 public:
     explicit CCoinsViewErrorCatcher(CCoinsView *view)
         : CCoinsViewBacked(view) {}
     bool GetCoin(const COutPoint &outpoint, Coin &coin) const override {
         try {
             return CCoinsViewBacked::GetCoin(outpoint, coin);
         } catch (const std::runtime_error &e) {
             uiInterface.ThreadSafeMessageBox(
                 _("Error reading from database, shutting down.").translated, "",
                 CClientUIInterface::MSG_ERROR);
             LogPrintf("Error reading from database: %s\n", e.what());
             // Starting the shutdown sequence and returning false to the caller
             // would be interpreted as 'entry not found' (as opposed to unable
             // to read data), and could lead to invalid interpretation. Just
             // exit immediately, as we can't continue anyway, and all writes
             // should be atomic.
             abort();
         }
     }
     // Writes do not need similar protection, as failure to write is handled by
     // the caller.
 };
 
 static std::unique_ptr<CCoinsViewErrorCatcher> pcoinscatcher;
 static std::unique_ptr<ECCVerifyHandle> globalVerifyHandle;
 
 static boost::thread_group threadGroup;
 static CScheduler scheduler;
 
 void Interrupt(NodeContext &node) {
     InterruptHTTPServer();
     InterruptHTTPRPC();
     InterruptRPC();
     InterruptREST();
     InterruptTorControl();
     InterruptMapPort();
     if (g_avalanche) {
         // Avalanche needs to be stopped before we interrupt the thread group as
         // the scheduler will stop working then.
         g_avalanche->stopEventLoop();
     }
     if (node.connman) {
         node.connman->Interrupt();
     }
     if (g_txindex) {
         g_txindex->Interrupt();
     }
     ForEachBlockFilterIndex([](BlockFilterIndex &index) { index.Interrupt(); });
 }
 
 void Shutdown(NodeContext &node) {
     LogPrintf("%s: In progress...\n", __func__);
     static RecursiveMutex cs_Shutdown;
     TRY_LOCK(cs_Shutdown, lockShutdown);
     if (!lockShutdown) {
         return;
     }
 
     /// Note: Shutdown() must be able to handle cases in which initialization
     /// failed part of the way, for example if the data directory was found to
     /// be locked. Be sure that anything that writes files or flushes caches
     /// only does this if the respective module was initialized.
     util::ThreadRename("shutoff");
     g_mempool.AddTransactionsUpdated(1);
 
     StopHTTPRPC();
     StopREST();
     StopRPC();
     StopHTTPServer();
     for (const auto &client : node.chain_clients) {
         client->flush();
     }
     StopMapPort();
 
     // Because avalanche and the network depend on each other, it is important
     // to shut them down in this order:
     // 1. Stop avalanche event loop.
     // 2. Shutdown network processing.
     // 3. Destroy AvalancheProcessor.
     // 4. Destroy CConnman
     if (g_avalanche) {
         g_avalanche->stopEventLoop();
     }
 
     // Because these depend on each-other, we make sure that neither can be
     // using the other before destroying them.
     if (node.peer_logic) {
         UnregisterValidationInterface(node.peer_logic.get());
     }
     if (node.connman) {
         node.connman->Stop();
     }
     if (g_txindex) {
         g_txindex->Stop();
     }
     ForEachBlockFilterIndex([](BlockFilterIndex &index) { index.Stop(); });
 
     StopTorControl();
 
     // After everything has been shut down, but before things get flushed, stop
     // the CScheduler/checkqueue threadGroup
     threadGroup.interrupt_all();
     threadGroup.join_all();
 
     // After the threads that potentially access these pointers have been
     // stopped, destruct and reset all to nullptr.
     node.peer_logic.reset();
 
     // Destroy various global instances
     g_avalanche.reset();
     node.connman.reset();
     node.banman.reset();
     g_txindex.reset();
     DestroyAllBlockFilterIndexes();
 
     if (::g_mempool.IsLoaded() &&
         gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
         DumpMempool(::g_mempool);
     }
 
     // FlushStateToDisk generates a ChainStateFlushed callback, which we should
     // avoid missing
     if (pcoinsTip != nullptr) {
         ::ChainstateActive().ForceFlushStateToDisk();
     }
 
     // After there are no more peers/RPC left to give us new data which may
     // generate CValidationInterface callbacks, flush them...
     GetMainSignals().FlushBackgroundCallbacks();
 
     // Any future callbacks will be dropped. This should absolutely be safe - if
     // missing a callback results in an unrecoverable situation, unclean
     // shutdown would too. The only reason to do the above flushes is to let the
     // wallet catch up with our current chain to avoid any strange pruning edge
     // cases and make next startup faster by avoiding rescan.
 
     {
         LOCK(cs_main);
         if (pcoinsTip != nullptr) {
             ::ChainstateActive().ForceFlushStateToDisk();
         }
         pcoinsTip.reset();
         pcoinscatcher.reset();
         pcoinsdbview.reset();
         pblocktree.reset();
     }
     for (const auto &client : node.chain_clients) {
         client->stop();
     }
 
 #if ENABLE_ZMQ
     if (g_zmq_notification_interface) {
         UnregisterValidationInterface(g_zmq_notification_interface);
         delete g_zmq_notification_interface;
         g_zmq_notification_interface = nullptr;
     }
 #endif
 
     try {
         if (!fs::remove(GetPidFile())) {
             LogPrintf("%s: Unable to remove PID file: File does not exist\n",
                       __func__);
         }
     } catch (const fs::filesystem_error &e) {
         LogPrintf("%s: Unable to remove PID file: %s\n", __func__,
                   fsbridge::get_filesystem_error_message(e));
     }
     node.chain_clients.clear();
     UnregisterAllValidationInterfaces();
     GetMainSignals().UnregisterBackgroundSignalScheduler();
     globalVerifyHandle.reset();
     ECC_Stop();
     if (node.mempool) {
         node.mempool = nullptr;
     }
     LogPrintf("%s: done\n", __func__);
 }
 
 /**
  * Signal handlers are very limited in what they are allowed to do.
  * The execution context the handler is invoked in is not guaranteed,
  * so we restrict handler operations to just touching variables:
  */
 #ifndef WIN32
 static void HandleSIGTERM(int) {
     StartShutdown();
 }
 
 static void HandleSIGHUP(int) {
     LogInstance().m_reopen_file = true;
 }
 #else
 static BOOL WINAPI consoleCtrlHandler(DWORD dwCtrlType) {
     StartShutdown();
     Sleep(INFINITE);
     return true;
 }
 #endif
 
 #ifndef WIN32
 static void registerSignalHandler(int signal, void (*handler)(int)) {
     struct sigaction sa;
     sa.sa_handler = handler;
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = 0;
     sigaction(signal, &sa, NULL);
 }
 #endif
 
 static void OnRPCStarted() {
     uiInterface.NotifyBlockTip_connect(&RPCNotifyBlockChange);
 }
 
 static void OnRPCStopped() {
     uiInterface.NotifyBlockTip_disconnect(&RPCNotifyBlockChange);
     RPCNotifyBlockChange(false, nullptr);
     g_best_block_cv.notify_all();
     LogPrint(BCLog::RPC, "RPC stopped.\n");
 }
 
 void SetupServerArgs() {
     const auto defaultBaseParams =
         CreateBaseChainParams(CBaseChainParams::MAIN);
     const auto testnetBaseParams =
         CreateBaseChainParams(CBaseChainParams::TESTNET);
     const auto regtestBaseParams =
         CreateBaseChainParams(CBaseChainParams::REGTEST);
     const auto defaultChainParams = CreateChainParams(CBaseChainParams::MAIN);
     const auto testnetChainParams =
         CreateChainParams(CBaseChainParams::TESTNET);
     const auto regtestChainParams =
         CreateChainParams(CBaseChainParams::REGTEST);
 
     // Hidden Options
     std::vector<std::string> hidden_args = {
         "-h", "-help", "-dbcrashratio", "-forcecompactdb", "-parkdeepreorg",
         "-automaticunparking", "-replayprotectionactivationtime",
         "-enableminerfund",
         // GUI args. These will be overwritten by SetupUIArgs for the GUI
         "-allowselfsignedrootcertificates", "-choosedatadir", "-lang=<lang>",
         "-min", "-resetguisettings", "-rootcertificates=<file>", "-splash",
         "-uiplatform",
         // TODO remove after the May 2020 upgrade
         "-phononactivationtime"};
 
     // Set all of the args and their help
     // When adding new options to the categories, please keep and ensure
     // alphabetical ordering. Do not translate _(...) -help-debug options, Many
     // technical terms, and only a very small audience, so is unnecessary stress
     // to translators.
     gArgs.AddArg("-?", "Print this help message and exit",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-version", "Print version and exit", ArgsManager::ALLOW_ANY,
                  OptionsCategory::OPTIONS);
     gArgs.AddArg("-alertnotify=<cmd>",
                  "Execute command when a relevant alert is received or we see "
                  "a really long fork (%s in cmd is replaced by message)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-assumevalid=<hex>",
         strprintf(
             "If this block is in the chain assume that it and its ancestors "
             "are valid and potentially skip their script verification (0 to "
             "verify all, default: %s, testnet: %s)",
             defaultChainParams->GetConsensus().defaultAssumeValid.GetHex(),
             testnetChainParams->GetConsensus().defaultAssumeValid.GetHex()),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-blocksdir=<dir>",
                  "Specify directory to hold blocks subdirectory for *.dat "
                  "files (default: <datadir>)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-blocknotify=<cmd>",
                  "Execute command when the best block changes (%s in cmd is "
                  "replaced by block hash)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-blockreconstructionextratxn=<n>",
                  strprintf("Extra transactions to keep in memory for compact "
                            "block reconstructions (default: %u)",
                            DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-blocksonly",
         strprintf(
             "Whether to reject transactions from network peers. Transactions "
             "from the wallet or RPC are not affected. (default: %u)",
             DEFAULT_BLOCKSONLY),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-conf=<file>",
                  strprintf("Specify configuration file. Relative paths will be "
                            "prefixed by datadir location. (default: %s)",
                            BITCOIN_CONF_FILENAME),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-datadir=<dir>", "Specify data directory",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-dbbatchsize",
         strprintf("Maximum database write batch size in bytes (default: %u)",
                   nDefaultDbBatchSize),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-dbcache=<n>",
         strprintf(
             "Set database cache size in megabytes (%d to %d, default: %d)",
             nMinDbCache, nMaxDbCache, nDefaultDbCache),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-debuglogfile=<file>",
                  strprintf("Specify location of debug log file. Relative paths "
                            "will be prefixed by a net-specific datadir "
                            "location. (0 to disable; default: %s)",
                            DEFAULT_DEBUGLOGFILE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-feefilter",
                  strprintf("Tell other nodes to filter invs to us by our "
                            "mempool min fee (default: %d)",
                            DEFAULT_FEEFILTER),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::OPTIONS);
     gArgs.AddArg("-finalizationdelay=<n>",
                  strprintf("Set the minimum amount of time to wait between a "
                            "block header reception and the block finalization. "
                            "Unit is seconds (default: %d)",
                            DEFAULT_MIN_FINALIZATION_DELAY),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-includeconf=<file>",
         "Specify additional configuration file, relative to the -datadir path "
         "(only useable from configuration file, not command line)",
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-maxreorgdepth=<n>",
                  strprintf("Configure at what depth blocks are considered "
                            "final (default: %d). Use -1 to disable.",
                            DEFAULT_MAX_REORG_DEPTH),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-loadblock=<file>",
                  "Imports blocks from external blk000??.dat file on startup",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-maxmempool=<n>",
                  strprintf("Keep the transaction memory pool below <n> "
                            "megabytes (default: %u)",
                            DEFAULT_MAX_MEMPOOL_SIZE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-maxorphantx=<n>",
                  strprintf("Keep at most <n> unconnectable transactions in "
                            "memory (default: %u)",
                            DEFAULT_MAX_ORPHAN_TRANSACTIONS),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-mempoolexpiry=<n>",
                  strprintf("Do not keep transactions in the mempool longer "
                            "than <n> hours (default: %u)",
                            DEFAULT_MEMPOOL_EXPIRY),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-minimumchainwork=<hex>",
         strprintf(
             "Minimum work assumed to exist on a valid chain in hex "
             "(default: %s, testnet: %s)",
             defaultChainParams->GetConsensus().nMinimumChainWork.GetHex(),
             testnetChainParams->GetConsensus().nMinimumChainWork.GetHex()),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-par=<n>",
         strprintf("Set the number of script verification threads (%u to %d, 0 "
                   "= auto, <0 = leave that many cores free, default: %d)",
                   -GetNumCores(), MAX_SCRIPTCHECK_THREADS,
                   DEFAULT_SCRIPTCHECK_THREADS),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-persistmempool",
                  strprintf("Whether to save the mempool on shutdown and load "
                            "on restart (default: %u)",
                            DEFAULT_PERSIST_MEMPOOL),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-pid=<file>",
                  strprintf("Specify pid file. Relative paths will be prefixed "
                            "by a net-specific datadir location. (default: %s)",
                            BITCOIN_PID_FILENAME),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-prune=<n>",
         strprintf("Reduce storage requirements by enabling pruning (deleting) "
                   "of old blocks. This allows the pruneblockchain RPC to be "
                   "called to delete specific blocks, and enables automatic "
                   "pruning of old blocks if a target size in MiB is provided. "
                   "This mode is incompatible with -txindex and -rescan. "
                   "Warning: Reverting this setting requires re-downloading the "
                   "entire blockchain. (default: 0 = disable pruning blocks, 1 "
                   "= allow manual pruning via RPC, >=%u = automatically prune "
                   "block files to stay under the specified target size in MiB)",
                   MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024),
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-reindex-chainstate",
                  "Rebuild chain state from the currently indexed blocks. When "
                  "in pruning mode or if blocks on disk might be corrupted, use "
                  "full -reindex instead.",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg(
         "-reindex",
         "Rebuild chain state and block index from the blk*.dat files on disk",
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #ifndef WIN32
     gArgs.AddArg(
         "-sysperms",
         "Create new files with system default permissions, instead of umask "
         "077 (only effective with disabled wallet functionality)",
         ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #else
     hidden_args.emplace_back("-sysperms");
 #endif
     gArgs.AddArg("-txindex",
                  strprintf("Maintain a full transaction index, used by the "
                            "getrawtransaction rpc call (default: %d)",
                            DEFAULT_TXINDEX),
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-blockfilterindex=<type>",
                  strprintf("Maintain an index of compact filters by block "
                            "(default: %s, values: %s).",
                            DEFAULT_BLOCKFILTERINDEX, ListBlockFilterTypes()) +
                      " If <type> is not supplied or if <type> = 1, indexes for "
                      "all known types are enabled.",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
     gArgs.AddArg("-usecashaddr",
                  "Use Cash Address for destination encoding instead of base58 "
                  "(activate by default on Jan, 14)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 
     gArgs.AddArg("-addnode=<ip>",
                  "Add a node to connect to and attempt to keep the connection "
                  "open (see the `addnode` RPC command help for more info)",
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-banscore=<n>",
         strprintf("Threshold for disconnecting misbehaving peers (default: %u)",
                   DEFAULT_BANSCORE_THRESHOLD),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-bantime=<n>",
                  strprintf("Number of seconds to keep misbehaving peers from "
                            "reconnecting (default: %u)",
                            DEFAULT_MISBEHAVING_BANTIME),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-bind=<addr>",
                  "Bind to given address and always listen on it. Use "
                  "[host]:port notation for IPv6",
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-connect=<ip>",
         "Connect only to the specified node(s); -connect=0 disables automatic "
         "connections (the rules for this peer are the same as for -addnode)",
         ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
         OptionsCategory::CONNECTION);
     gArgs.AddArg("-discover",
                  "Discover own IP addresses (default: 1 when listening and no "
                  "-externalip or -proxy)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-dns",
                  strprintf("Allow DNS lookups for -addnode, -seednode and "
                            "-connect (default: %d)",
                            DEFAULT_NAME_LOOKUP),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-dnsseed",
                  "Query for peer addresses via DNS lookup, if low on addresses "
                  "(default: 1 unless -connect used)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-enablebip61",
                  strprintf("Send reject messages per BIP61 (default: %u)",
                            DEFAULT_ENABLE_BIP61),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 
     gArgs.AddArg("-externalip=<ip>", "Specify your own public address",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-forcednsseed",
         strprintf(
             "Always query for peer addresses via DNS lookup (default: %d)",
             DEFAULT_FORCEDNSSEED),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-listen",
         "Accept connections from outside (default: 1 if no -proxy or -connect)",
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-listenonion",
         strprintf("Automatically create Tor hidden service (default: %d)",
                   DEFAULT_LISTEN_ONION),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxconnections=<n>",
         strprintf("Maintain at most <n> connections to peers (default: %u)",
                   DEFAULT_MAX_PEER_CONNECTIONS),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-maxreceivebuffer=<n>",
                  strprintf("Maximum per-connection receive buffer, <n>*1000 "
                            "bytes (default: %u)",
                            DEFAULT_MAXRECEIVEBUFFER),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxsendbuffer=<n>",
         strprintf(
             "Maximum per-connection send buffer, <n>*1000 bytes (default: %u)",
             DEFAULT_MAXSENDBUFFER),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxtimeadjustment",
         strprintf("Maximum allowed median peer time offset adjustment. Local "
                   "perspective of time may be influenced by peers forward or "
                   "backward by this amount. (default: %u seconds)",
                   DEFAULT_MAX_TIME_ADJUSTMENT),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-onion=<ip:port>",
                  strprintf("Use separate SOCKS5 proxy to reach peers via Tor "
                            "hidden services (default: %s)",
                            "-proxy"),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-onlynet=<net>",
                  "Only connect to nodes in network <net> (ipv4, ipv6 or onion)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-peerbloomfilters",
                  strprintf("Support filtering of blocks and transaction with "
                            "bloom filters (default: %d)",
                            DEFAULT_PEERBLOOMFILTERS),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-permitbaremultisig",
                  strprintf("Relay non-P2SH multisig (default: %d)",
                            DEFAULT_PERMIT_BAREMULTISIG),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-port=<port>",
                  strprintf("Listen for connections on <port> (default: %u, "
                            "testnet: %u, regtest: %u)",
                            defaultChainParams->GetDefaultPort(),
                            testnetChainParams->GetDefaultPort(),
                            regtestChainParams->GetDefaultPort()),
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::CONNECTION);
     gArgs.AddArg("-proxy=<ip:port>", "Connect through SOCKS5 proxy",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-proxyrandomize",
                  strprintf("Randomize credentials for every proxy connection. "
                            "This enables Tor stream isolation (default: %d)",
                            DEFAULT_PROXYRANDOMIZE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-seednode=<ip>",
                  "Connect to a node to retrieve peer addresses, and disconnect",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-timeout=<n>",
                  strprintf("Specify connection timeout in milliseconds "
                            "(minimum: 1, default: %d)",
                            DEFAULT_CONNECT_TIMEOUT),
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-peertimeout=<n>",
         strprintf("Specify p2p connection timeout in seconds. This option "
                   "determines the amount of time a peer may be inactive before "
                   "the connection to it is dropped. (minimum: 1, default: %d)",
                   DEFAULT_PEER_CONNECT_TIMEOUT),
         true, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-torcontrol=<ip>:<port>",
         strprintf(
             "Tor control port to use if onion listening enabled (default: %s)",
             DEFAULT_TOR_CONTROL),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-torpassword=<pass>",
                  "Tor control port password (default: empty)",
                  ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE,
                  OptionsCategory::CONNECTION);
 #ifdef USE_UPNP
 #if USE_UPNP
     gArgs.AddArg("-upnp",
                  "Use UPnP to map the listening port (default: 1 when "
                  "listening and no -proxy)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 #else
     gArgs.AddArg(
         "-upnp",
         strprintf("Use UPnP to map the listening port (default: %u)", 0),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 #endif
 #else
     hidden_args.emplace_back("-upnp");
 #endif
     gArgs.AddArg("-whitebind=<addr>",
                  "Bind to given address and whitelist peers connecting to it. "
                  "Use [host]:port notation for IPv6",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg("-whitelist=<IP address or network>",
                  "Whitelist peers connecting from the given IP address (e.g. "
                  "1.2.3.4) or CIDR notated network (e.g. 1.2.3.0/24). Can be "
                  "specified multiple times. "
                  "Whitelisted peers cannot be DoS banned and their "
                  "transactions are always relayed, even if they are already in "
                  "the mempool, useful e.g. for a gateway",
                  ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
     gArgs.AddArg(
         "-maxuploadtarget=<n>",
         strprintf("Tries to keep outbound traffic under the given target (in "
                   "MiB per 24h), 0 = no limit (default: %d)",
                   DEFAULT_MAX_UPLOAD_TARGET),
         ArgsManager::ALLOW_ANY, OptionsCategory::CONNECTION);
 
     g_wallet_init_interface.AddWalletOptions();
 
 #if ENABLE_ZMQ
     gArgs.AddArg("-zmqpubhashblock=<address>",
                  "Enable publish hash block in <address>",
                  ArgsManager::ALLOW_ANY, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubhashtx=<address>",
                  "Enable publish hash transaction in <address>",
                  ArgsManager::ALLOW_ANY, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubrawblock=<address>",
                  "Enable publish raw block in <address>",
                  ArgsManager::ALLOW_ANY, OptionsCategory::ZMQ);
     gArgs.AddArg("-zmqpubrawtx=<address>",
                  "Enable publish raw transaction in <address>",
                  ArgsManager::ALLOW_ANY, OptionsCategory::ZMQ);
+    gArgs.AddArg("-zmqpubhashblockhwm=<n>",
+                 strprintf("Set publish hash block outbound message high water "
+                           "mark (default: %d)",
+                           CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM),
+                 false, OptionsCategory::ZMQ);
+    gArgs.AddArg("-zmqpubhashtxhwm=<n>",
+                 strprintf("Set publish hash transaction outbound message high "
+                           "water mark (default: %d)",
+                           CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM),
+                 false, OptionsCategory::ZMQ);
+    gArgs.AddArg("-zmqpubrawblockhwm=<n>",
+                 strprintf("Set publish raw block outbound message high water "
+                           "mark (default: %d)",
+                           CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM),
+                 false, OptionsCategory::ZMQ);
+    gArgs.AddArg("-zmqpubrawtxhwm=<n>",
+                 strprintf("Set publish raw transaction outbound message high "
+                           "water mark (default: %d)",
+                           CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM),
+                 false, OptionsCategory::ZMQ);
 #else
     hidden_args.emplace_back("-zmqpubhashblock=<address>");
     hidden_args.emplace_back("-zmqpubhashtx=<address>");
     hidden_args.emplace_back("-zmqpubrawblock=<address>");
     hidden_args.emplace_back("-zmqpubrawtx=<address>");
+    hidden_args.emplace_back("-zmqpubhashblockhwm=<n>");
+    hidden_args.emplace_back("-zmqpubhashtxhwm=<n>");
+    hidden_args.emplace_back("-zmqpubrawblockhwm=<n>");
+    hidden_args.emplace_back("-zmqpubrawtxhwm=<n>");
 #endif
 
     gArgs.AddArg(
         "-checkblocks=<n>",
         strprintf("How many blocks to check at startup (default: %u, 0 = all)",
                   DEFAULT_CHECKBLOCKS),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-checklevel=<n>",
         strprintf("How thorough the block verification of "
                   "-checkblocks is: "
                   "level 0 reads the blocks from disk, "
                   "level 1 verifies block validity, "
                   "level 2 verifies undo data, "
                   "level 3 checks disconnection of tip blocks, "
                   "and level 4 tries to reconnect the blocks. "
                   "Each level includes the checks of the previous levels "
                   "(0-4, default: %u)",
                   DEFAULT_CHECKLEVEL),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-checkblockindex",
         strprintf("Do a full consistency check for mapBlockIndex, "
                   "setBlockIndexCandidates, ::ChainActive() and "
                   "mapBlocksUnlinked occasionally. (default: %u, regtest: %u)",
                   defaultChainParams->DefaultConsistencyChecks(),
                   regtestChainParams->DefaultConsistencyChecks()),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-checkmempool=<n>",
         strprintf(
             "Run checks every <n> transactions (default: %u, regtest: %u)",
             defaultChainParams->DefaultConsistencyChecks(),
             regtestChainParams->DefaultConsistencyChecks()),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-checkpoints",
                  strprintf("Only accept block chain matching built-in "
                            "checkpoints (default: %d)",
                            DEFAULT_CHECKPOINTS_ENABLED),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-deprecatedrpc=<method>",
                  "Allows deprecated RPC method(s) to be used",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-dropmessagestest=<n>",
                  "Randomly drop 1 of every <n> network messages",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-stopafterblockimport",
         strprintf("Stop running after importing blocks from disk (default: %d)",
                   DEFAULT_STOPAFTERBLOCKIMPORT),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-stopatheight",
                  strprintf("Stop running after reaching the given height in "
                            "the main chain (default: %u)",
                            DEFAULT_STOPATHEIGHT),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-limitancestorcount=<n>",
                  strprintf("Do not accept transactions if number of in-mempool "
                            "ancestors is <n> or more (pre-phonon-upgrade "
                            "default: %u, post-phonon-upgrade default: %u)",
                            DEFAULT_ANCESTOR_LIMIT,
                            DEFAULT_ANCESTOR_LIMIT_LONGER),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-limitancestorsize=<n>",
         strprintf("Do not accept transactions whose size with all in-mempool "
                   "ancestors exceeds <n> kilobytes (default: %u)",
                   DEFAULT_ANCESTOR_SIZE_LIMIT),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-limitdescendantcount=<n>",
         strprintf("Do not accept transactions if any ancestor would have <n> "
                   "or more in-mempool descendants (default pre-phonon-upgrade: "
                   "%u, default post-phonon-upgrade: %u)",
                   DEFAULT_DESCENDANT_LIMIT, DEFAULT_DESCENDANT_LIMIT_LONGER),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-limitdescendantsize=<n>",
         strprintf("Do not accept transactions if any ancestor would have more "
                   "than <n> kilobytes of in-mempool descendants (default: %u).",
                   DEFAULT_DESCENDANT_SIZE_LIMIT),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-addrmantest", "Allows to test address relay on localhost",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg("-debug=<category>",
                  strprintf("Output debugging information (default: %u, "
                            "supplying <category> is optional)",
                            0) +
                      ". " +
                      "If <category> is not supplied or if <category> = 1, "
                      "output all debugging information."
                      "<category> can be: " +
                      ListLogCategories() + ".",
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-debugexclude=<category>",
         strprintf("Exclude debugging information for a category. Can be used "
                   "in conjunction with -debug=1 to output debug logs for all "
                   "categories except one or more specified categories."),
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-help-debug",
                  "Print help message with debugging options and exit",
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logips",
                  strprintf("Include IP addresses in debug output (default: %d)",
                            DEFAULT_LOGIPS),
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logtimestamps",
                  strprintf("Prepend debug output with timestamp (default: %d)",
                            DEFAULT_LOGTIMESTAMPS),
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-logthreadnames",
         strprintf(
             "Prepend debug output with name of the originating thread (only "
             "available on platforms supporting thread_local) (default: %u)",
             DEFAULT_LOGTHREADNAMES),
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-logtimemicros",
         strprintf("Add microsecond precision to debug timestamps (default: %d)",
                   DEFAULT_LOGTIMEMICROS),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-mocktime=<n>",
         "Replace actual time with <n> seconds since epoch (default: 0)",
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-maxsigcachesize=<n>",
         strprintf("Limit size of signature cache to <n> MiB (default: %u)",
                   DEFAULT_MAX_SIG_CACHE_SIZE),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-maxscriptcachesize=<n>",
         strprintf("Limit size of script cache to <n> MiB (default: %u)",
                   DEFAULT_MAX_SCRIPT_CACHE_SIZE),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-maxtipage=<n>",
                  strprintf("Maximum tip age in seconds to consider node in "
                            "initial block download (default: %u)",
                            DEFAULT_MAX_TIP_AGE),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg(
         "-printtoconsole",
         "Send trace/debug info to console instead of debug.log file (default: "
         "1 when no -daemon. To disable logging to file, set debuglogfile=0)",
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-printpriority",
                  strprintf("Log transaction priority and fee per kB when "
                            "mining blocks (default: %d)",
                            DEFAULT_PRINTPRIORITY),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::DEBUG_TEST);
     gArgs.AddArg(
         "-shrinkdebugfile",
         "Shrink debug.log file on client startup (default: 1 when no -debug)",
         ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
 
     gArgs.AddArg("-uacomment=<cmt>", "Append comment to the user agent string",
                  ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
 
     SetupChainParamsBaseOptions();
 
     gArgs.AddArg(
         "-acceptnonstdtxn",
         strprintf(
             "Relay and mine \"non-standard\" transactions (%sdefault: %u)",
             "testnet/regtest only; ", defaultChainParams->RequireStandard()),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::NODE_RELAY);
     gArgs.AddArg("-excessiveblocksize=<n>",
                  strprintf("Do not accept blocks larger than this limit, in "
                            "bytes (default: %d)",
                            DEFAULT_MAX_BLOCK_SIZE),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-dustrelayfee=<amt>",
         strprintf("Fee rate (in %s/kB) used to defined dust, the value of an "
                   "output such that it will cost about 1/3 of its value in "
                   "fees at this fee rate to spend it. (default: %s)",
                   CURRENCY_UNIT, FormatMoney(DUST_RELAY_TX_FEE)),
         ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
         OptionsCategory::NODE_RELAY);
 
     gArgs.AddArg("-bytespersigop",
                  strprintf("Equivalent bytes per sigop in transactions for "
                            "relay and mining (default: %u)",
                            DEFAULT_BYTES_PER_SIGOP),
                  ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-datacarrier",
         strprintf("Relay and mine data carrier transactions (default: %d)",
                   DEFAULT_ACCEPT_DATACARRIER),
         ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg("-datacarriersize",
                  strprintf("Maximum size of data in data carrier transactions "
                            "we relay and mine (default: %u)",
                            MAX_OP_RETURN_RELAY),
                  ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-minrelaytxfee=<amt>",
         strprintf("Fees (in %s/kB) smaller than this are rejected for "
                   "relaying, mining and transaction creation (default: %s)",
                   CURRENCY_UNIT, FormatMoney(DEFAULT_MIN_RELAY_TX_FEE_PER_KB)),
         ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-whitelistrelay",
         strprintf("Accept relayed transactions received from whitelisted "
                   "peers even when not relaying transactions (default: %d)",
                   DEFAULT_WHITELISTRELAY),
         ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     gArgs.AddArg(
         "-whitelistforcerelay",
         strprintf("Force relay of transactions from whitelisted peers even if "
                   "they violate local relay policy (default: %d)",
                   DEFAULT_WHITELISTFORCERELAY),
         ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
 
     // Not sure this really belongs here, but it will do for now.
     // FIXME: This doesn't work anyways.
     gArgs.AddArg("-excessutxocharge=<amt>",
                  strprintf("Fees (in %s/kB) to charge per utxo created for "
                            "relaying, and mining (default: %s)",
                            CURRENCY_UNIT, FormatMoney(DEFAULT_UTXO_FEE)),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::NODE_RELAY);
 
     gArgs.AddArg("-blockmaxsize=<n>",
                  strprintf("Set maximum block size in bytes (default: %d)",
                            DEFAULT_MAX_GENERATED_BLOCK_SIZE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::BLOCK_CREATION);
     gArgs.AddArg("-blockmintxfee=<amt>",
                  strprintf("Set lowest fee rate (in %s/kB) for transactions to "
                            "be included in block creation. (default: %s)",
                            CURRENCY_UNIT,
                            FormatMoney(DEFAULT_BLOCK_MIN_TX_FEE_PER_KB)),
                  ArgsManager::ALLOW_ANY, OptionsCategory::BLOCK_CREATION);
 
     gArgs.AddArg("-blockversion=<n>",
                  "Override block version to test forking scenarios",
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::BLOCK_CREATION);
 
     gArgs.AddArg("-server", "Accept command line and JSON-RPC commands",
                  ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg("-rest",
                  strprintf("Accept public REST requests (default: %d)",
                            DEFAULT_REST_ENABLE),
                  ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcbind=<addr>[:port]",
         "Bind to given address to listen for JSON-RPC connections. Do not "
         "expose the RPC server to untrusted networks such as the public "
         "internet! This option is ignored unless -rpcallowip is also passed. "
         "Port is optional and overrides -rpcport.  Use [host]:port notation "
         "for IPv6. This option can be specified multiple times (default: "
         "127.0.0.1 and ::1 i.e., localhost)",
         ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY |
             ArgsManager::SENSITIVE,
         OptionsCategory::RPC);
     gArgs.AddArg("-rpccookiefile=<loc>",
                  "Location of the auth cookie. Relative paths will be prefixed "
                  "by a net-specific datadir location. (default: data dir)",
                  ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg("-rpcuser=<user>", "Username for JSON-RPC connections",
                  ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE,
                  OptionsCategory::RPC);
     gArgs.AddArg("-rpcpassword=<pw>", "Password for JSON-RPC connections",
                  ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE,
                  OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcwhitelist=<whitelist>",
         "Set a whitelist to filter incoming RPC calls for a specific user. The "
         "field <whitelist> comes in the format: <USERNAME>:<rpc 1>,<rpc "
         "2>,...,<rpc n>. If multiple whitelists are set for a given user, they "
         "are set-intersected. See -rpcwhitelistdefault documentation for "
         "information on default whitelist behavior.",
         ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcwhitelistdefault",
         "Sets default behavior for rpc whitelisting. Unless "
         "rpcwhitelistdefault is set to 0, if any -rpcwhitelist is set, the rpc "
         "server acts as if all rpc users are subject to "
         "empty-unless-otherwise-specified whitelists. If rpcwhitelistdefault "
         "is set to 1 and no -rpcwhitelist is set, rpc server acts as if all "
         "rpc users are subject to empty whitelists.",
         ArgsManager::ALLOW_BOOL, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcauth=<userpw>",
         "Username and hashed password for JSON-RPC connections. The field "
         "<userpw> comes in the format: <USERNAME>:<SALT>$<HASH>. A canonical "
         "python script is included in share/rpcauth. The client then connects "
         "normally using the rpcuser=<USERNAME>/rpcpassword=<PASSWORD> pair of "
         "arguments. This option can be specified multiple times",
         ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE, OptionsCategory::RPC);
     gArgs.AddArg("-rpcport=<port>",
                  strprintf("Listen for JSON-RPC connections on <port> "
                            "(default: %u, testnet: %u, regtest: %u)",
                            defaultBaseParams->RPCPort(),
                            testnetBaseParams->RPCPort(),
                            regtestBaseParams->RPCPort()),
                  ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY,
                  OptionsCategory::RPC);
     gArgs.AddArg("-rpcallowip=<ip>",
                  "Allow JSON-RPC connections from specified source. Valid for "
                  "<ip> are a single IP (e.g. 1.2.3.4), a network/netmask (e.g. "
                  "1.2.3.4/255.255.255.0) or a network/CIDR (e.g. 1.2.3.4/24). "
                  "This option can be specified multiple times",
                  ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpcthreads=<n>",
         strprintf(
             "Set the number of threads to service RPC calls (default: %d)",
             DEFAULT_HTTP_THREADS),
         ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     gArgs.AddArg(
         "-rpccorsdomain=value",
         "Domain from which to accept cross origin requests (browser enforced)",
         ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
 
     gArgs.AddArg("-rpcworkqueue=<n>",
                  strprintf("Set the depth of the work queue to service RPC "
                            "calls (default: %d)",
                            DEFAULT_HTTP_WORKQUEUE),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::RPC);
     gArgs.AddArg("-rpcservertimeout=<n>",
                  strprintf("Timeout during HTTP requests (default: %d)",
                            DEFAULT_HTTP_SERVER_TIMEOUT),
                  ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY,
                  OptionsCategory::RPC);
 
 #if HAVE_DECL_DAEMON
     gArgs.AddArg("-daemon",
                  "Run in the background as a daemon and accept commands",
                  ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
 #else
     hidden_args.emplace_back("-daemon");
 #endif
 
     // Avalanche options.
     gArgs.AddArg(
         "-enableavalanche",
         strprintf("Enable avalanche (default: %u)", AVALANCHE_DEFAULT_ENABLED),
         ArgsManager::ALLOW_ANY, OptionsCategory::AVALANCHE);
     gArgs.AddArg(
         "-avacooldown",
         strprintf("Mandatory cooldown between two avapoll (default: %u)",
                   AVALANCHE_DEFAULT_COOLDOWN),
         ArgsManager::ALLOW_ANY, OptionsCategory::AVALANCHE);
 
     // Add the hidden options
     gArgs.AddHiddenArgs(hidden_args);
 }
 
 std::string LicenseInfo() {
     const std::string URL_SOURCE_CODE =
         "<https://github.com/Bitcoin-ABC/bitcoin-abc>";
     const std::string URL_WEBSITE = "<https://www.bitcoinabc.org>";
 
     return CopyrightHolders(strprintf(_("Copyright (C) %i-%i").translated, 2009,
                                       COPYRIGHT_YEAR) +
                             " ") +
            "\n" + "\n" +
            strprintf(_("Please contribute if you find %s useful. "
                        "Visit %s for further information about the software.")
                          .translated,
                      PACKAGE_NAME, URL_WEBSITE) +
            "\n" +
            strprintf(_("The source code is available from %s.").translated,
                      URL_SOURCE_CODE) +
            "\n" + "\n" + _("This is experimental software.").translated + "\n" +
            strprintf(_("Distributed under the MIT software license, see the "
                        "accompanying file %s or %s")
                          .translated,
                      "COPYING", "<https://opensource.org/licenses/MIT>") +
            "\n" + "\n" +
            strprintf(_("This product includes software developed by the "
                        "OpenSSL Project for use in the OpenSSL Toolkit %s and "
                        "cryptographic software written by Eric Young and UPnP "
                        "software written by Thomas Bernard.")
                          .translated,
                      "<https://www.openssl.org>") +
            "\n";
 }
 
 static void BlockNotifyCallback(bool initialSync,
                                 const CBlockIndex *pBlockIndex) {
     if (initialSync || !pBlockIndex) {
         return;
     }
 
     std::string strCmd = gArgs.GetArg("-blocknotify", "");
     if (!strCmd.empty()) {
         boost::replace_all(strCmd, "%s", pBlockIndex->GetBlockHash().GetHex());
         std::thread t(runCommand, strCmd);
         // thread runs free
         t.detach();
     }
 }
 
 static bool fHaveGenesis = false;
 static Mutex g_genesis_wait_mutex;
 static std::condition_variable g_genesis_wait_cv;
 
 static void BlockNotifyGenesisWait(bool, const CBlockIndex *pBlockIndex) {
     if (pBlockIndex != nullptr) {
         {
             LOCK(g_genesis_wait_mutex);
             fHaveGenesis = true;
         }
         g_genesis_wait_cv.notify_all();
     }
 }
 
 struct CImportingNow {
     CImportingNow() {
         assert(fImporting == false);
         fImporting = true;
     }
 
     ~CImportingNow() {
         assert(fImporting == true);
         fImporting = false;
     }
 };
 
 // If we're using -prune with -reindex, then delete block files that will be
 // ignored by the reindex.  Since reindexing works by starting at block file 0
 // and looping until a blockfile is missing, do the same here to delete any
 // later block files after a gap. Also delete all rev files since they'll be
 // rewritten by the reindex anyway. This ensures that vinfoBlockFile is in sync
 // with what's actually on disk by the time we start downloading, so that
 // pruning works correctly.
 static void CleanupBlockRevFiles() {
     std::map<std::string, fs::path> mapBlockFiles;
 
     // Glob all blk?????.dat and rev?????.dat files from the blocks directory.
     // Remove the rev files immediately and insert the blk file paths into an
     // ordered map keyed by block file index.
     LogPrintf("Removing unusable blk?????.dat and rev?????.dat files for "
               "-reindex with -prune\n");
     const auto directoryIterator = fs::directory_iterator{GetBlocksDir()};
     for (const auto &file : directoryIterator) {
         const auto fileName = file.path().filename().string();
         if (fs::is_regular_file(file) && fileName.length() == 12 &&
             fileName.substr(8, 4) == ".dat") {
             if (fileName.substr(0, 3) == "blk") {
                 mapBlockFiles[fileName.substr(3, 5)] = file.path();
             } else if (fileName.substr(0, 3) == "rev") {
                 remove(file.path());
             }
         }
     }
 
     // Remove all block files that aren't part of a contiguous set starting at
     // zero by walking the ordered map (keys are block file indices) by keeping
     // a separate counter. Once we hit a gap (or if 0 doesn't exist) start
     // removing block files.
     int contiguousCounter = 0;
     for (const auto &item : mapBlockFiles) {
         if (atoi(item.first) == contiguousCounter) {
             contiguousCounter++;
             continue;
         }
         remove(item.second);
     }
 }
 
 static void ThreadImport(const Config &config,
                          std::vector<fs::path> vImportFiles) {
     util::ThreadRename("loadblk");
     ScheduleBatchPriority();
 
     {
         const CChainParams &chainParams = config.GetChainParams();
 
         CImportingNow imp;
 
         // -reindex
         if (fReindex) {
             int nFile = 0;
             while (true) {
                 FlatFilePos pos(nFile, 0);
                 if (!fs::exists(GetBlockPosFilename(pos))) {
                     // No block files left to reindex
                     break;
                 }
                 FILE *file = OpenBlockFile(pos, true);
                 if (!file) {
                     // This error is logged in OpenBlockFile
                     break;
                 }
                 LogPrintf("Reindexing block file blk%05u.dat...\n",
                           (unsigned int)nFile);
                 LoadExternalBlockFile(config, file, &pos);
                 nFile++;
             }
             pblocktree->WriteReindexing(false);
             fReindex = false;
             LogPrintf("Reindexing finished\n");
             // To avoid ending up in a situation without genesis block, re-try
             // initializing (no-op if reindexing worked):
             LoadGenesisBlock(chainParams);
         }
 
         // hardcoded $DATADIR/bootstrap.dat
         fs::path pathBootstrap = GetDataDir() / "bootstrap.dat";
         if (fs::exists(pathBootstrap)) {
             FILE *file = fsbridge::fopen(pathBootstrap, "rb");
             if (file) {
                 fs::path pathBootstrapOld = GetDataDir() / "bootstrap.dat.old";
                 LogPrintf("Importing bootstrap.dat...\n");
                 LoadExternalBlockFile(config, file);
                 RenameOver(pathBootstrap, pathBootstrapOld);
             } else {
                 LogPrintf("Warning: Could not open bootstrap file %s\n",
                           pathBootstrap.string());
             }
         }
 
         // -loadblock=
         for (const fs::path &path : vImportFiles) {
             FILE *file = fsbridge::fopen(path, "rb");
             if (file) {
                 LogPrintf("Importing blocks file %s...\n", path.string());
                 LoadExternalBlockFile(config, file);
             } else {
                 LogPrintf("Warning: Could not open blocks file %s\n",
                           path.string());
             }
         }
 
         // Reconsider blocks we know are valid. They may have been marked
         // invalid by, for instance, running an outdated version of the node
         // software.
         const MapCheckpoints &checkpoints =
             chainParams.Checkpoints().mapCheckpoints;
         for (const MapCheckpoints::value_type &i : checkpoints) {
             const BlockHash &hash = i.second;
 
             LOCK(cs_main);
             CBlockIndex *pblockindex = LookupBlockIndex(hash);
             if (pblockindex && !pblockindex->nStatus.isValid()) {
                 LogPrintf("Reconsidering checkpointed block %s ...\n",
                           hash.GetHex());
                 ResetBlockFailureFlags(pblockindex);
             }
         }
 
         // scan for better chains in the block chain database, that are not yet
         // connected in the active best chain
         CValidationState state;
         if (!ActivateBestChain(config, state)) {
             LogPrintf("Failed to connect best block (%s)\n",
                       FormatStateMessage(state));
             StartShutdown();
             return;
         }
 
         if (gArgs.GetBoolArg("-stopafterblockimport",
                              DEFAULT_STOPAFTERBLOCKIMPORT)) {
             LogPrintf("Stopping after block import\n");
             StartShutdown();
             return;
         }
     } // End scope of CImportingNow
     if (gArgs.GetArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
         LoadMempool(config, ::g_mempool);
     }
     ::g_mempool.SetIsLoaded(!ShutdownRequested());
 }
 
 /** Sanity checks
  *  Ensure that Bitcoin is running in a usable environment with all
  *  necessary library support.
  */
 static bool InitSanityCheck() {
     if (!ECC_InitSanityCheck()) {
         InitError(
             "Elliptic curve cryptography sanity check failure. Aborting.");
         return false;
     }
 
     if (!glibcxx_sanity_test()) {
         return false;
     }
 
     if (!Random_SanityCheck()) {
         InitError("OS cryptographic RNG sanity check failure. Aborting.");
         return false;
     }
 
     return true;
 }
 
 static bool AppInitServers(Config &config,
                            HTTPRPCRequestProcessor &httpRPCRequestProcessor) {
     RPCServerSignals::OnStarted(&OnRPCStarted);
     RPCServerSignals::OnStopped(&OnRPCStopped);
     if (!InitHTTPServer(config)) {
         return false;
     }
 
     StartRPC();
 
     if (!StartHTTPRPC(httpRPCRequestProcessor)) {
         return false;
     }
     if (gArgs.GetBoolArg("-rest", DEFAULT_REST_ENABLE)) {
         StartREST();
     }
 
     StartHTTPServer();
     return true;
 }
 
 // Parameter interaction based on rules
 void InitParameterInteraction() {
     // when specifying an explicit binding address, you want to listen on it
     // even when -connect or -proxy is specified.
     if (gArgs.IsArgSet("-bind")) {
         if (gArgs.SoftSetBoolArg("-listen", true)) {
             LogPrintf(
                 "%s: parameter interaction: -bind set -> setting -listen=1\n",
                 __func__);
         }
     }
     if (gArgs.IsArgSet("-whitebind")) {
         if (gArgs.SoftSetBoolArg("-listen", true)) {
             LogPrintf("%s: parameter interaction: -whitebind set -> setting "
                       "-listen=1\n",
                       __func__);
         }
     }
 
     if (gArgs.IsArgSet("-connect")) {
         // when only connecting to trusted nodes, do not seed via DNS, or listen
         // by default.
         if (gArgs.SoftSetBoolArg("-dnsseed", false)) {
             LogPrintf("%s: parameter interaction: -connect set -> setting "
                       "-dnsseed=0\n",
                       __func__);
         }
         if (gArgs.SoftSetBoolArg("-listen", false)) {
             LogPrintf("%s: parameter interaction: -connect set -> setting "
                       "-listen=0\n",
                       __func__);
         }
     }
 
     if (gArgs.IsArgSet("-proxy")) {
         // to protect privacy, do not listen by default if a default proxy
         // server is specified.
         if (gArgs.SoftSetBoolArg("-listen", false)) {
             LogPrintf(
                 "%s: parameter interaction: -proxy set -> setting -listen=0\n",
                 __func__);
         }
         // to protect privacy, do not use UPNP when a proxy is set. The user may
         // still specify -listen=1 to listen locally, so don't rely on this
         // happening through -listen below.
         if (gArgs.SoftSetBoolArg("-upnp", false)) {
             LogPrintf(
                 "%s: parameter interaction: -proxy set -> setting -upnp=0\n",
                 __func__);
         }
         // to protect privacy, do not discover addresses by default
         if (gArgs.SoftSetBoolArg("-discover", false)) {
             LogPrintf("%s: parameter interaction: -proxy set -> setting "
                       "-discover=0\n",
                       __func__);
         }
     }
 
     if (!gArgs.GetBoolArg("-listen", DEFAULT_LISTEN)) {
         // do not map ports or try to retrieve public IP when not listening
         // (pointless)
         if (gArgs.SoftSetBoolArg("-upnp", false)) {
             LogPrintf(
                 "%s: parameter interaction: -listen=0 -> setting -upnp=0\n",
                 __func__);
         }
         if (gArgs.SoftSetBoolArg("-discover", false)) {
             LogPrintf(
                 "%s: parameter interaction: -listen=0 -> setting -discover=0\n",
                 __func__);
         }
         if (gArgs.SoftSetBoolArg("-listenonion", false)) {
             LogPrintf("%s: parameter interaction: -listen=0 -> setting "
                       "-listenonion=0\n",
                       __func__);
         }
     }
 
     if (gArgs.IsArgSet("-externalip")) {
         // if an explicit public IP is specified, do not try to find others
         if (gArgs.SoftSetBoolArg("-discover", false)) {
             LogPrintf("%s: parameter interaction: -externalip set -> setting "
                       "-discover=0\n",
                       __func__);
         }
     }
 
     // disable whitelistrelay in blocksonly mode
     if (gArgs.GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY)) {
         if (gArgs.SoftSetBoolArg("-whitelistrelay", false)) {
             LogPrintf("%s: parameter interaction: -blocksonly=1 -> setting "
                       "-whitelistrelay=0\n",
                       __func__);
         }
     }
 
     // Forcing relay from whitelisted hosts implies we will accept relays from
     // them in the first place.
     if (gArgs.GetBoolArg("-whitelistforcerelay", DEFAULT_WHITELISTFORCERELAY)) {
         if (gArgs.SoftSetBoolArg("-whitelistrelay", true)) {
             LogPrintf("%s: parameter interaction: -whitelistforcerelay=1 -> "
                       "setting -whitelistrelay=1\n",
                       __func__);
         }
     }
 }
 
 static std::string ResolveErrMsg(const char *const optname,
                                  const std::string &strBind) {
     return strprintf(_("Cannot resolve -%s address: '%s'").translated, optname,
                      strBind);
 }
 
 /**
  * Initialize global loggers.
  *
  * Note that this is called very early in the process lifetime, so you should be
  * careful about what global state you rely on here.
  */
 void InitLogging() {
     LogInstance().m_print_to_file = !gArgs.IsArgNegated("-debuglogfile");
     LogInstance().m_file_path = AbsPathForConfigVal(
         gArgs.GetArg("-debuglogfile", DEFAULT_DEBUGLOGFILE));
 
     LogInstance().m_print_to_console = gArgs.GetBoolArg(
         "-printtoconsole", !gArgs.GetBoolArg("-daemon", false));
     LogInstance().m_log_timestamps =
         gArgs.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
     LogInstance().m_log_time_micros =
         gArgs.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
     LogInstance().m_log_threadnames =
         gArgs.GetBoolArg("-logthreadnames", DEFAULT_LOGTHREADNAMES);
 
     fLogIPs = gArgs.GetBoolArg("-logips", DEFAULT_LOGIPS);
 
     std::string version_string = FormatFullVersion();
 #ifdef DEBUG
     version_string += " (debug build)";
 #else
     version_string += " (release build)";
 #endif
     LogPrintf("%s version %s\n", CLIENT_NAME, version_string);
 }
 
 namespace { // Variables internal to initialization process only
 
 int nMaxConnections;
 int nUserMaxConnections;
 int nFD;
 ServiceFlags nLocalServices = ServiceFlags(NODE_NETWORK | NODE_NETWORK_LIMITED);
 int64_t peer_connect_timeout;
 std::vector<BlockFilterType> g_enabled_filter_types;
 
 } // namespace
 
 [[noreturn]] static void new_handler_terminate() {
     // Rather than throwing std::bad-alloc if allocation fails, terminate
     // immediately to (try to) avoid chain corruption. Since LogPrintf may
     // itself allocate memory, set the handler directly to terminate first.
     std::set_new_handler(std::terminate);
     LogPrintf("Error: Out of memory. Terminating.\n");
 
     // The log was successful, terminate now.
     std::terminate();
 };
 
 bool AppInitBasicSetup() {
 // Step 1: setup
 #ifdef _MSC_VER
     // Turn off Microsoft heap dump noise
     _CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_FILE);
     _CrtSetReportFile(_CRT_WARN, CreateFileA("NUL", GENERIC_WRITE, 0, nullptr,
                                              OPEN_EXISTING, 0, 0));
     // Disable confusing "helpful" text message on abort, Ctrl-C
     _set_abort_behavior(0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT);
 #endif
 #ifdef WIN32
 // Enable Data Execution Prevention (DEP)
 // Minimum supported OS versions: WinXP SP3, WinVista >= SP1, Win Server 2008
 // A failure is non-critical and needs no further attention!
 #ifndef PROCESS_DEP_ENABLE
 // We define this here, because GCCs winbase.h limits this to _WIN32_WINNT >=
 // 0x0601 (Windows 7), which is not correct. Can be removed, when GCCs winbase.h
 // is fixed!
 #define PROCESS_DEP_ENABLE 0x00000001
 #endif
     typedef BOOL(WINAPI * PSETPROCDEPPOL)(DWORD);
     PSETPROCDEPPOL setProcDEPPol = (PSETPROCDEPPOL)GetProcAddress(
         GetModuleHandleA("Kernel32.dll"), "SetProcessDEPPolicy");
     if (setProcDEPPol != nullptr) {
         setProcDEPPol(PROCESS_DEP_ENABLE);
     }
 #endif
 
     if (!SetupNetworking()) {
         return InitError("Initializing networking failed");
     }
 
 #ifndef WIN32
     if (!gArgs.GetBoolArg("-sysperms", false)) {
         umask(077);
     }
 
     // Clean shutdown on SIGTERM
     registerSignalHandler(SIGTERM, HandleSIGTERM);
     registerSignalHandler(SIGINT, HandleSIGTERM);
 
     // Reopen debug.log on SIGHUP
     registerSignalHandler(SIGHUP, HandleSIGHUP);
 
     // Ignore SIGPIPE, otherwise it will bring the daemon down if the client
     // closes unexpectedly
     signal(SIGPIPE, SIG_IGN);
 #else
     SetConsoleCtrlHandler(consoleCtrlHandler, true);
 #endif
 
     std::set_new_handler(new_handler_terminate);
 
     return true;
 }
 
 bool AppInitParameterInteraction(Config &config) {
     const CChainParams &chainparams = config.GetChainParams();
     // Step 2: parameter interactions
 
     // also see: InitParameterInteraction()
 
     // Warn if network-specific options (-addnode, -connect, etc) are
     // specified in default section of config file, but not overridden
     // on the command line or in this network's section of the config file.
     std::string network = gArgs.GetChainName();
     for (const auto &arg : gArgs.GetUnsuitableSectionOnlyArgs()) {
         return InitError(strprintf(_("Config setting for %s only applied on %s "
                                      "network when in [%s] section.")
                                        .translated,
                                    arg, network, network));
     }
 
     // Warn if unrecognized section name are present in the config file.
     for (const auto &section : gArgs.GetUnrecognizedSections()) {
         InitWarning(strprintf(
             "%s:%i " + _("Section [%s] is not recognized.").translated,
             section.m_file, section.m_line, section.m_name));
     }
 
     if (!fs::is_directory(GetBlocksDir())) {
         return InitError(strprintf(
             _("Specified blocks directory \"%s\" does not exist.").translated,
             gArgs.GetArg("-blocksdir", "")));
     }
 
     // parse and validate enabled filter types
     std::string blockfilterindex_value =
         gArgs.GetArg("-blockfilterindex", DEFAULT_BLOCKFILTERINDEX);
     if (blockfilterindex_value == "" || blockfilterindex_value == "1") {
         g_enabled_filter_types = AllBlockFilterTypes();
     } else if (blockfilterindex_value != "0") {
         const std::vector<std::string> names =
             gArgs.GetArgs("-blockfilterindex");
         g_enabled_filter_types.reserve(names.size());
         for (const auto &name : names) {
             BlockFilterType filter_type;
             if (!BlockFilterTypeByName(name, filter_type)) {
                 return InitError(strprintf(
                     _("Unknown -blockfilterindex value %s.").translated, name));
             }
             g_enabled_filter_types.push_back(filter_type);
         }
     }
 
     // if using block pruning, then disallow txindex
     if (gArgs.GetArg("-prune", 0)) {
         if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
             return InitError(
                 _("Prune mode is incompatible with -txindex.").translated);
         }
         if (!g_enabled_filter_types.empty()) {
             return InitError(
                 _("Prune mode is incompatible with -blockfilterindex.")
                     .translated);
         }
     }
 
     // -bind and -whitebind can't be set when not listening
     size_t nUserBind =
         gArgs.GetArgs("-bind").size() + gArgs.GetArgs("-whitebind").size();
     if (nUserBind != 0 && !gArgs.GetBoolArg("-listen", DEFAULT_LISTEN)) {
         return InitError(
             "Cannot set -bind or -whitebind together with -listen=0");
     }
 
     // Make sure enough file descriptors are available
     int nBind = std::max(nUserBind, size_t(1));
     nUserMaxConnections =
         gArgs.GetArg("-maxconnections", DEFAULT_MAX_PEER_CONNECTIONS);
     nMaxConnections = std::max(nUserMaxConnections, 0);
 
     // Trim requested connection counts, to fit into system limitations
     nMaxConnections =
         std::max(std::min(nMaxConnections, FD_SETSIZE - nBind -
                                                MIN_CORE_FILEDESCRIPTORS -
                                                MAX_ADDNODE_CONNECTIONS),
                  0);
     nFD = RaiseFileDescriptorLimit(nMaxConnections + MIN_CORE_FILEDESCRIPTORS +
                                    MAX_ADDNODE_CONNECTIONS);
     if (nFD < MIN_CORE_FILEDESCRIPTORS) {
         return InitError(
             _("Not enough file descriptors available.").translated);
     }
     nMaxConnections =
         std::min(nFD - MIN_CORE_FILEDESCRIPTORS - MAX_ADDNODE_CONNECTIONS,
                  nMaxConnections);
 
     if (nMaxConnections < nUserMaxConnections) {
         InitWarning(strprintf(_("Reducing -maxconnections from %d to %d, "
                                 "because of system limitations.")
                                   .translated,
                               nUserMaxConnections, nMaxConnections));
     }
 
     // Step 3: parameter-to-internal-flags
     if (gArgs.IsArgSet("-debug")) {
         // Special-case: if -debug=0/-nodebug is set, turn off debugging
         // messages
         const std::vector<std::string> &categories = gArgs.GetArgs("-debug");
         if (std::none_of(
                 categories.begin(), categories.end(),
                 [](std::string cat) { return cat == "0" || cat == "none"; })) {
             for (const auto &cat : categories) {
                 if (!LogInstance().EnableCategory(cat)) {
                     InitWarning(strprintf(
                         _("Unsupported logging category %s=%s.").translated,
                         "-debug", cat));
                 }
             }
         }
     }
 
     // Now remove the logging categories which were explicitly excluded
     for (const std::string &cat : gArgs.GetArgs("-debugexclude")) {
         if (!LogInstance().DisableCategory(cat)) {
             InitWarning(
                 strprintf(_("Unsupported logging category %s=%s.").translated,
                           "-debugexclude", cat));
         }
     }
 
     // Checkmempool and checkblockindex default to true in regtest mode
     int ratio = std::min<int>(
         std::max<int>(
             gArgs.GetArg("-checkmempool",
                          chainparams.DefaultConsistencyChecks() ? 1 : 0),
             0),
         1000000);
     if (ratio != 0) {
         g_mempool.setSanityCheck(1.0 / ratio);
     }
     fCheckBlockIndex = gArgs.GetBoolArg("-checkblockindex",
                                         chainparams.DefaultConsistencyChecks());
     fCheckpointsEnabled =
         gArgs.GetBoolArg("-checkpoints", DEFAULT_CHECKPOINTS_ENABLED);
     if (fCheckpointsEnabled) {
         LogPrintf("Checkpoints will be verified.\n");
     } else {
         LogPrintf("Skipping checkpoint verification.\n");
     }
 
     hashAssumeValid = BlockHash::fromHex(
         gArgs.GetArg("-assumevalid",
                      chainparams.GetConsensus().defaultAssumeValid.GetHex()));
     if (!hashAssumeValid.IsNull()) {
         LogPrintf("Assuming ancestors of block %s have valid signatures.\n",
                   hashAssumeValid.GetHex());
     } else {
         LogPrintf("Validating signatures for all blocks.\n");
     }
 
     if (gArgs.IsArgSet("-minimumchainwork")) {
         const std::string minChainWorkStr =
             gArgs.GetArg("-minimumchainwork", "");
         if (!IsHexNumber(minChainWorkStr)) {
             return InitError(strprintf(
                 "Invalid non-hex (%s) minimum chain work value specified",
                 minChainWorkStr));
         }
         nMinimumChainWork = UintToArith256(uint256S(minChainWorkStr));
     } else {
         nMinimumChainWork =
             UintToArith256(chainparams.GetConsensus().nMinimumChainWork);
     }
     LogPrintf("Setting nMinimumChainWork=%s\n", nMinimumChainWork.GetHex());
     if (nMinimumChainWork <
         UintToArith256(chainparams.GetConsensus().nMinimumChainWork)) {
         LogPrintf("Warning: nMinimumChainWork set below default value of %s\n",
                   chainparams.GetConsensus().nMinimumChainWork.GetHex());
     }
 
     // mempool limits
     int64_t nMempoolSizeMax =
         gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
     int64_t nMempoolSizeMin =
         gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT) *
         1000 * 40;
     if (nMempoolSizeMax < 0 || nMempoolSizeMax < nMempoolSizeMin) {
         return InitError(
             strprintf(_("-maxmempool must be at least %d MB").translated,
                       std::ceil(nMempoolSizeMin / 1000000.0)));
     }
 
     // -par=0 means autodetect, but nScriptCheckThreads==0 means no concurrency
     nScriptCheckThreads = gArgs.GetArg("-par", DEFAULT_SCRIPTCHECK_THREADS);
     if (nScriptCheckThreads <= 0) {
         nScriptCheckThreads += GetNumCores();
     }
     if (nScriptCheckThreads <= 1) {
         nScriptCheckThreads = 0;
     } else if (nScriptCheckThreads > MAX_SCRIPTCHECK_THREADS) {
         nScriptCheckThreads = MAX_SCRIPTCHECK_THREADS;
     }
 
     // Configure excessive block size.
     const uint64_t nProposedExcessiveBlockSize =
         gArgs.GetArg("-excessiveblocksize", DEFAULT_MAX_BLOCK_SIZE);
     if (!config.SetMaxBlockSize(nProposedExcessiveBlockSize)) {
         return InitError(
             _("Excessive block size must be > 1,000,000 bytes (1MB)")
                 .translated);
     }
 
     // Check blockmaxsize does not exceed maximum accepted block size.
     const uint64_t nProposedMaxGeneratedBlockSize =
         gArgs.GetArg("-blockmaxsize", DEFAULT_MAX_GENERATED_BLOCK_SIZE);
     if (nProposedMaxGeneratedBlockSize > config.GetMaxBlockSize()) {
         auto msg = _("Max generated block size (blockmaxsize) cannot exceed "
                      "the excessive block size (excessiveblocksize)")
                        .translated;
         return InitError(msg);
     }
 
     // block pruning; get the amount of disk space (in MiB) to allot for block &
     // undo files
     int64_t nPruneArg = gArgs.GetArg("-prune", 0);
     if (nPruneArg < 0) {
         return InitError(
             _("Prune cannot be configured with a negative value.").translated);
     }
     nPruneTarget = (uint64_t)nPruneArg * 1024 * 1024;
     if (nPruneArg == 1) {
         // manual pruning: -prune=1
         LogPrintf("Block pruning enabled.  Use RPC call "
                   "pruneblockchain(height) to manually prune block and undo "
                   "files.\n");
         nPruneTarget = std::numeric_limits<uint64_t>::max();
         fPruneMode = true;
     } else if (nPruneTarget) {
         if (nPruneTarget < MIN_DISK_SPACE_FOR_BLOCK_FILES) {
             return InitError(
                 strprintf(_("Prune configured below the minimum of %d MiB. "
                             "Please use a higher number.")
                               .translated,
                           MIN_DISK_SPACE_FOR_BLOCK_FILES / 1024 / 1024));
         }
         LogPrintf("Prune configured to target %uMiB on disk for block and undo "
                   "files.\n",
                   nPruneTarget / 1024 / 1024);
         fPruneMode = true;
     }
 
     nConnectTimeout = gArgs.GetArg("-timeout", DEFAULT_CONNECT_TIMEOUT);
     if (nConnectTimeout <= 0) {
         nConnectTimeout = DEFAULT_CONNECT_TIMEOUT;
     }
 
     peer_connect_timeout =
         gArgs.GetArg("-peertimeout", DEFAULT_PEER_CONNECT_TIMEOUT);
     if (peer_connect_timeout <= 0) {
         return InitError(
             "peertimeout cannot be configured with a negative value.");
     }
 
     // Obtain the amount to charge excess UTXO
     if (gArgs.IsArgSet("-excessutxocharge")) {
         Amount n = Amount::zero();
         auto parsed = ParseMoney(gArgs.GetArg("-excessutxocharge", ""), n);
         if (!parsed || Amount::zero() > n) {
             return InitError(AmountErrMsg(
                 "excessutxocharge", gArgs.GetArg("-excessutxocharge", "")));
         }
         config.SetExcessUTXOCharge(n);
     } else {
         config.SetExcessUTXOCharge(DEFAULT_UTXO_FEE);
     }
 
     if (gArgs.IsArgSet("-minrelaytxfee")) {
         Amount n = Amount::zero();
         auto parsed = ParseMoney(gArgs.GetArg("-minrelaytxfee", ""), n);
         if (!parsed || n == Amount::zero()) {
             return InitError(AmountErrMsg("minrelaytxfee",
                                           gArgs.GetArg("-minrelaytxfee", "")));
         }
         // High fee check is done afterward in WalletParameterInteraction()
         ::minRelayTxFee = CFeeRate(n);
     }
 
     // Sanity check argument for min fee for including tx in block
     // TODO: Harmonize which arguments need sanity checking and where that
     // happens.
     if (gArgs.IsArgSet("-blockmintxfee")) {
         Amount n = Amount::zero();
         if (!ParseMoney(gArgs.GetArg("-blockmintxfee", ""), n)) {
             return InitError(AmountErrMsg("blockmintxfee",
                                           gArgs.GetArg("-blockmintxfee", "")));
         }
     }
 
     // Feerate used to define dust.  Shouldn't be changed lightly as old
     // implementations may inadvertently create non-standard transactions.
     if (gArgs.IsArgSet("-dustrelayfee")) {
         Amount n = Amount::zero();
         auto parsed = ParseMoney(gArgs.GetArg("-dustrelayfee", ""), n);
         if (!parsed || Amount::zero() == n) {
             return InitError(AmountErrMsg("dustrelayfee",
                                           gArgs.GetArg("-dustrelayfee", "")));
         }
         dustRelayFee = CFeeRate(n);
     }
 
     fRequireStandard =
         !gArgs.GetBoolArg("-acceptnonstdtxn", !chainparams.RequireStandard());
     if (!chainparams.IsTestChain() && !fRequireStandard) {
         return InitError(
             strprintf("acceptnonstdtxn is not currently supported for %s chain",
                       chainparams.NetworkIDString()));
     }
     nBytesPerSigOp = gArgs.GetArg("-bytespersigop", nBytesPerSigOp);
 
     if (!g_wallet_init_interface.ParameterInteraction()) {
         return false;
     }
 
     fIsBareMultisigStd =
         gArgs.GetBoolArg("-permitbaremultisig", DEFAULT_PERMIT_BAREMULTISIG);
     fAcceptDatacarrier =
         gArgs.GetBoolArg("-datacarrier", DEFAULT_ACCEPT_DATACARRIER);
 
     // Option to startup with mocktime set (used for regression testing):
     SetMockTime(gArgs.GetArg("-mocktime", 0)); // SetMockTime(0) is a no-op
 
     if (gArgs.GetBoolArg("-peerbloomfilters", DEFAULT_PEERBLOOMFILTERS)) {
         nLocalServices = ServiceFlags(nLocalServices | NODE_BLOOM);
     }
 
     // Signal Bitcoin Cash support.
     // TODO: remove some time after the hardfork when no longer needed
     // to differentiate the network nodes.
     nLocalServices = ServiceFlags(nLocalServices | NODE_BITCOIN_CASH);
 
     nMaxTipAge = gArgs.GetArg("-maxtipage", DEFAULT_MAX_TIP_AGE);
 
     return true;
 }
 
 static bool LockDataDirectory(bool probeOnly) {
     // Make sure only a single Bitcoin process is using the data directory.
     fs::path datadir = GetDataDir();
     if (!DirIsWritable(datadir)) {
         return InitError(strprintf(
             _("Cannot write to data directory '%s'; check permissions.")
                 .translated,
             datadir.string()));
     }
     if (!LockDirectory(datadir, ".lock", probeOnly)) {
         return InitError(strprintf(_("Cannot obtain a lock on data directory "
                                      "%s. %s is probably already running.")
                                        .translated,
                                    datadir.string(), PACKAGE_NAME));
     }
     return true;
 }
 
 bool AppInitSanityChecks() {
     // Step 4: sanity checks
 
     // Initialize elliptic curve code
     std::string sha256_algo = SHA256AutoDetect();
     LogPrintf("Using the '%s' SHA256 implementation\n", sha256_algo);
     RandomInit();
     ECC_Start();
     globalVerifyHandle.reset(new ECCVerifyHandle());
 
     // Sanity check
     if (!InitSanityCheck()) {
         return InitError(strprintf(
             _("Initialization sanity check failed. %s is shutting down.")
                 .translated,
             PACKAGE_NAME));
     }
 
     // Probe the data directory lock to give an early error message, if possible
     // We cannot hold the data directory lock here, as the forking for daemon()
     // hasn't yet happened, and a fork will cause weird behavior to it.
     return LockDataDirectory(true);
 }
 
 bool AppInitLockDataDirectory() {
     // After daemonization get the data directory lock again and hold on to it
     // until exit. This creates a slight window for a race condition to happen,
     // however this condition is harmless: it will at most make us exit without
     // printing a message to console.
     if (!LockDataDirectory(false)) {
         // Detailed error printed inside LockDataDirectory
         return false;
     }
     return true;
 }
 
 bool AppInitMain(Config &config, RPCServer &rpcServer,
                  HTTPRPCRequestProcessor &httpRPCRequestProcessor,
                  NodeContext &node) {
     // Step 4a: application initialization
     const CChainParams &chainparams = config.GetChainParams();
 
     if (!CreatePidFile()) {
         // Detailed error printed inside CreatePidFile().
         return false;
     }
 
     BCLog::Logger &logger = LogInstance();
     if (logger.m_print_to_file) {
         if (gArgs.GetBoolArg("-shrinkdebugfile",
                              logger.DefaultShrinkDebugFile())) {
             // Do this first since it both loads a bunch of debug.log into
             // memory, and because this needs to happen before any other
             // debug.log printing.
             logger.ShrinkDebugFile();
         }
     }
 
     if (!logger.StartLogging()) {
         return InitError(strprintf("Could not open debug log file %s",
                                    logger.m_file_path.string()));
     }
 
     if (!logger.m_log_timestamps) {
         LogPrintf("Startup time: %s\n", FormatISO8601DateTime(GetTime()));
     }
     LogPrintf("Default data directory %s\n", GetDefaultDataDir().string());
     LogPrintf("Using data directory %s\n", GetDataDir().string());
 
     // Only log conf file usage message if conf file actually exists.
     fs::path config_file_path =
         GetConfigFile(gArgs.GetArg("-conf", BITCOIN_CONF_FILENAME));
     if (fs::exists(config_file_path)) {
         LogPrintf("Config file: %s\n", config_file_path.string());
     } else if (gArgs.IsArgSet("-conf")) {
         // Warn if no conf file exists at path provided by user
         InitWarning(strprintf(
             _("The specified config file %s does not exist\n").translated,
             config_file_path.string()));
     } else {
         // Not categorizing as "Warning" because it's the default behavior
         LogPrintf("Config file: %s (not found, skipping)\n",
                   config_file_path.string());
     }
 
     // Log the config arguments to debug.log
     gArgs.LogArgs();
 
     LogPrintf("Using at most %i automatic connections (%i file descriptors "
               "available)\n",
               nMaxConnections, nFD);
 
     // Warn about relative -datadir path.
     if (gArgs.IsArgSet("-datadir") &&
         !fs::path(gArgs.GetArg("-datadir", "")).is_absolute()) {
         LogPrintf("Warning: relative datadir option '%s' specified, which will "
                   "be interpreted relative to the current working directory "
                   "'%s'. This is fragile, because if bitcoin is started in the "
                   "future from a different location, it will be unable to "
                   "locate the current data files. There could also be data "
                   "loss if bitcoin is started while in a temporary "
                   "directory.\n",
                   gArgs.GetArg("-datadir", ""), fs::current_path().string());
     }
 
     InitSignatureCache();
     InitScriptExecutionCache();
 
     LogPrintf("Using %u threads for script verification\n",
               nScriptCheckThreads);
     if (nScriptCheckThreads) {
         for (int i = 0; i < nScriptCheckThreads - 1; i++) {
             threadGroup.create_thread([i]() { return ThreadScriptCheck(i); });
         }
     }
 
     // Start the lightweight task scheduler thread
     CScheduler::Function serviceLoop =
         std::bind(&CScheduler::serviceQueue, &scheduler);
     threadGroup.create_thread(std::bind(&TraceThread<CScheduler::Function>,
                                         "scheduler", serviceLoop));
 
     // Gather some entropy once per minute.
     scheduler.scheduleEvery(
         [] {
             RandAddPeriodic();
             return true;
         },
         60000);
 
     GetMainSignals().RegisterBackgroundSignalScheduler(scheduler);
 
     // Create client interfaces for wallets that are supposed to be loaded
     // according to -wallet and -disablewallet options. This only constructs
     // the interfaces, it doesn't load wallet data. Wallets actually get loaded
     // when load() and start() interface methods are called below.
     g_wallet_init_interface.Construct(node);
 
     /**
      * Register RPC commands regardless of -server setting so they will be
      * available in the GUI RPC console even if external calls are disabled.
      */
     RegisterAllRPCCommands(config, rpcServer, tableRPC);
     for (const auto &client : node.chain_clients) {
         client->registerRpcs();
     }
     g_rpc_node = &node;
 #if ENABLE_ZMQ
     RegisterZMQRPCCommands(tableRPC);
 #endif
 
     /**
      * Start the RPC server.  It will be started in "warmup" mode and not
      * process calls yet (but it will verify that the server is there and will
      * be ready later).  Warmup mode will be completed when initialisation is
      * finished.
      */
     if (gArgs.GetBoolArg("-server", false)) {
         uiInterface.InitMessage_connect(SetRPCWarmupStatus);
         if (!AppInitServers(config, httpRPCRequestProcessor)) {
             return InitError(
                 _("Unable to start HTTP server. See debug log for details.")
                     .translated);
         }
     }
 
     // Step 5: verify wallet database integrity
     for (const auto &client : node.chain_clients) {
         if (!client->verify(chainparams)) {
             return false;
         }
     }
 
     // Step 6: network initialization
 
     // Note that we absolutely cannot open any actual connections
     // until the very end ("start node") as the UTXO/block state
     // is not yet setup and may end up being set up twice if we
     // need to reindex later.
 
     assert(!node.banman);
     node.banman = std::make_unique<BanMan>(
         GetDataDir() / "banlist.dat", config.GetChainParams(), &uiInterface,
         gArgs.GetArg("-bantime", DEFAULT_MISBEHAVING_BANTIME));
     assert(!node.connman);
     node.connman = std::make_unique<CConnman>(
         config, GetRand(std::numeric_limits<uint64_t>::max()),
         GetRand(std::numeric_limits<uint64_t>::max()));
 
     node.peer_logic = std::make_unique<PeerLogicValidation>(
         node.connman.get(), node.banman.get(), scheduler,
         gArgs.GetBoolArg("-enablebip61", DEFAULT_ENABLE_BIP61));
     RegisterValidationInterface(node.peer_logic.get());
 
     // sanitize comments per BIP-0014, format user agent and check total size
     std::vector<std::string> uacomments;
     for (const std::string &cmt : gArgs.GetArgs("-uacomment")) {
         if (cmt != SanitizeString(cmt, SAFE_CHARS_UA_COMMENT)) {
             return InitError(strprintf(
                 _("User Agent comment (%s) contains unsafe characters.")
                     .translated,
                 cmt));
         }
         uacomments.push_back(cmt);
     }
     const std::string strSubVersion =
         FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, uacomments);
     if (strSubVersion.size() > MAX_SUBVERSION_LENGTH) {
         return InitError(strprintf(
             _("Total length of network version string (%i) exceeds maximum "
               "length (%i). Reduce the number or size of uacomments.")
                 .translated,
             strSubVersion.size(), MAX_SUBVERSION_LENGTH));
     }
 
     if (gArgs.IsArgSet("-onlynet")) {
         std::set<enum Network> nets;
         for (const std::string &snet : gArgs.GetArgs("-onlynet")) {
             enum Network net = ParseNetwork(snet);
             if (net == NET_UNROUTABLE) {
                 return InitError(strprintf(
                     _("Unknown network specified in -onlynet: '%s'").translated,
                     snet));
             }
             nets.insert(net);
         }
         for (int n = 0; n < NET_MAX; n++) {
             enum Network net = (enum Network)n;
             if (!nets.count(net)) {
                 SetReachable(net, false);
             }
         }
     }
 
     // Check for host lookup allowed before parsing any network related
     // parameters
     fNameLookup = gArgs.GetBoolArg("-dns", DEFAULT_NAME_LOOKUP);
 
     bool proxyRandomize =
         gArgs.GetBoolArg("-proxyrandomize", DEFAULT_PROXYRANDOMIZE);
     // -proxy sets a proxy for all outgoing network traffic
     // -noproxy (or -proxy=0) as well as the empty string can be used to not set
     // a proxy, this is the default
     std::string proxyArg = gArgs.GetArg("-proxy", "");
     SetReachable(NET_ONION, false);
     if (proxyArg != "" && proxyArg != "0") {
         CService proxyAddr;
         if (!Lookup(proxyArg.c_str(), proxyAddr, 9050, fNameLookup)) {
             return InitError(strprintf(
                 _("Invalid -proxy address or hostname: '%s'").translated,
                 proxyArg));
         }
 
         proxyType addrProxy = proxyType(proxyAddr, proxyRandomize);
         if (!addrProxy.IsValid()) {
             return InitError(strprintf(
                 _("Invalid -proxy address or hostname: '%s'").translated,
                 proxyArg));
         }
 
         SetProxy(NET_IPV4, addrProxy);
         SetProxy(NET_IPV6, addrProxy);
         SetProxy(NET_ONION, addrProxy);
         SetNameProxy(addrProxy);
         // by default, -proxy sets onion as reachable, unless -noonion later
         SetReachable(NET_ONION, true);
     }
 
     // -onion can be used to set only a proxy for .onion, or override normal
     // proxy for .onion addresses.
     // -noonion (or -onion=0) disables connecting to .onion entirely. An empty
     // string is used to not override the onion proxy (in which case it defaults
     // to -proxy set above, or none)
     std::string onionArg = gArgs.GetArg("-onion", "");
     if (onionArg != "") {
         if (onionArg == "0") {
             // Handle -noonion/-onion=0
             SetReachable(NET_ONION, false);
         } else {
             CService onionProxy;
             if (!Lookup(onionArg.c_str(), onionProxy, 9050, fNameLookup)) {
                 return InitError(strprintf(
                     _("Invalid -onion address or hostname: '%s'").translated,
                     onionArg));
             }
             proxyType addrOnion = proxyType(onionProxy, proxyRandomize);
             if (!addrOnion.IsValid()) {
                 return InitError(strprintf(
                     _("Invalid -onion address or hostname: '%s'").translated,
                     onionArg));
             }
             SetProxy(NET_ONION, addrOnion);
             SetReachable(NET_ONION, true);
         }
     }
 
     // see Step 2: parameter interactions for more information about these
     fListen = gArgs.GetBoolArg("-listen", DEFAULT_LISTEN);
     fDiscover = gArgs.GetBoolArg("-discover", true);
     g_relay_txes = !gArgs.GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY);
 
     for (const std::string &strAddr : gArgs.GetArgs("-externalip")) {
         CService addrLocal;
         if (Lookup(strAddr.c_str(), addrLocal, GetListenPort(), fNameLookup) &&
             addrLocal.IsValid()) {
             AddLocal(addrLocal, LOCAL_MANUAL);
         } else {
             return InitError(ResolveErrMsg("externalip", strAddr));
         }
     }
 
 #if ENABLE_ZMQ
     g_zmq_notification_interface = CZMQNotificationInterface::Create();
 
     if (g_zmq_notification_interface) {
         RegisterValidationInterface(g_zmq_notification_interface);
     }
 #endif
     // unlimited unless -maxuploadtarget is set
     uint64_t nMaxOutboundLimit = 0;
     uint64_t nMaxOutboundTimeframe = MAX_UPLOAD_TIMEFRAME;
 
     if (gArgs.IsArgSet("-maxuploadtarget")) {
         nMaxOutboundLimit =
             gArgs.GetArg("-maxuploadtarget", DEFAULT_MAX_UPLOAD_TARGET) * 1024 *
             1024;
     }
 
     // Step 6.5 (I guess ?): Initialize Avalanche.
     g_avalanche = std::make_unique<AvalancheProcessor>(node.connman.get());
 
     // Step 7: load block chain
 
     fReindex = gArgs.GetBoolArg("-reindex", false);
     bool fReindexChainState = gArgs.GetBoolArg("-reindex-chainstate", false);
 
     // cache size calculations
     int64_t nTotalCache = (gArgs.GetArg("-dbcache", nDefaultDbCache) << 20);
     // total cache cannot be less than nMinDbCache
     nTotalCache = std::max(nTotalCache, nMinDbCache << 20);
     // total cache cannot be greater than nMaxDbcache
     nTotalCache = std::min(nTotalCache, nMaxDbCache << 20);
     int64_t nBlockTreeDBCache =
         std::min(nTotalCache / 8, nMaxBlockDBCache << 20);
     nTotalCache -= nBlockTreeDBCache;
     int64_t nTxIndexCache =
         std::min(nTotalCache / 8, gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)
                                       ? nMaxTxIndexCache << 20
                                       : 0);
     nTotalCache -= nTxIndexCache;
     int64_t filter_index_cache = 0;
     if (!g_enabled_filter_types.empty()) {
         size_t n_indexes = g_enabled_filter_types.size();
         int64_t max_cache =
             std::min(nTotalCache / 8, max_filter_index_cache << 20);
         filter_index_cache = max_cache / n_indexes;
         nTotalCache -= filter_index_cache * n_indexes;
     }
     // use 25%-50% of the remainder for disk cache
     int64_t nCoinDBCache =
         std::min(nTotalCache / 2, (nTotalCache / 4) + (1 << 23));
     // cap total coins db cache
     nCoinDBCache = std::min(nCoinDBCache, nMaxCoinsDBCache << 20);
     nTotalCache -= nCoinDBCache;
     // the rest goes to in-memory cache
     nCoinCacheUsage = nTotalCache;
     int64_t nMempoolSizeMax =
         gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000;
     LogPrintf("Cache configuration:\n");
     LogPrintf("* Using %.1fMiB for block index database\n",
               nBlockTreeDBCache * (1.0 / 1024 / 1024));
     if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
         LogPrintf("* Using %.1fMiB for transaction index database\n",
                   nTxIndexCache * (1.0 / 1024 / 1024));
     }
     for (BlockFilterType filter_type : g_enabled_filter_types) {
         LogPrintf("* Using %.1f MiB for %s block filter index database\n",
                   filter_index_cache * (1.0 / 1024 / 1024),
                   BlockFilterTypeName(filter_type));
     }
     LogPrintf("* Using %.1fMiB for chain state database\n",
               nCoinDBCache * (1.0 / 1024 / 1024));
     LogPrintf("* Using %.1fMiB for in-memory UTXO set (plus up to %.1fMiB of "
               "unused mempool space)\n",
               nCoinCacheUsage * (1.0 / 1024 / 1024),
               nMempoolSizeMax * (1.0 / 1024 / 1024));
 
     int64_t nStart = 0;
     bool fLoaded = false;
     while (!fLoaded && !ShutdownRequested()) {
         bool fReset = fReindex;
         std::string strLoadError;
 
         uiInterface.InitMessage(_("Loading block index...").translated);
         nStart = GetTimeMillis();
         do {
             try {
                 LOCK(cs_main);
                 UnloadBlockIndex();
                 pcoinsTip.reset();
                 pcoinsdbview.reset();
                 pcoinscatcher.reset();
                 pblocktree.reset(
                     new CBlockTreeDB(nBlockTreeDBCache, false, fReset));
 
                 if (fReset) {
                     pblocktree->WriteReindexing(true);
                     // If we're reindexing in prune mode, wipe away unusable
                     // block files and all undo data files
                     if (fPruneMode) {
                         CleanupBlockRevFiles();
                     }
                 }
 
                 if (ShutdownRequested()) {
                     break;
                 }
 
                 const Consensus::Params &params = chainparams.GetConsensus();
 
                 // LoadBlockIndex will load fHavePruned if we've ever removed a
                 // block file from disk.
                 // Note that it also sets fReindex based on the disk flag!
                 // From here on out fReindex and fReset mean something
                 // different!
                 if (!LoadBlockIndex(params)) {
                     strLoadError = _("Error loading block database").translated;
                     break;
                 }
 
                 // If the loaded chain has a wrong genesis, bail out immediately
                 // (we're likely using a testnet datadir, or the other way
                 // around).
                 if (!mapBlockIndex.empty() &&
                     !LookupBlockIndex(params.hashGenesisBlock)) {
                     return InitError(_("Incorrect or no genesis block found. "
                                        "Wrong datadir for network?")
                                          .translated);
                 }
 
                 // Check for changed -prune state.  What we are concerned about
                 // is a user who has pruned blocks in the past, but is now
                 // trying to run unpruned.
                 if (fHavePruned && !fPruneMode) {
                     strLoadError =
                         _("You need to rebuild the database using -reindex to "
                           "go back to unpruned mode.  This will redownload the "
                           "entire blockchain")
                             .translated;
                     break;
                 }
 
                 // At this point blocktree args are consistent with what's on
                 // disk. If we're not mid-reindex (based on disk + args), add a
                 // genesis block on disk (otherwise we use the one already on
                 // disk).
                 // This is called again in ThreadImport after the reindex
                 // completes.
                 if (!fReindex && !LoadGenesisBlock(chainparams)) {
                     strLoadError =
                         _("Error initializing block database").translated;
                     break;
                 }
 
                 // At this point we're either in reindex or we've loaded a
                 // useful block tree into mapBlockIndex!
 
                 pcoinsdbview.reset(new CCoinsViewDB(
                     nCoinDBCache, false, fReset || fReindexChainState));
                 pcoinscatcher.reset(
                     new CCoinsViewErrorCatcher(pcoinsdbview.get()));
 
                 // If necessary, upgrade from older database format.
                 // This is a no-op if we cleared the coinsviewdb with -reindex
                 // or -reindex-chainstate
                 if (!pcoinsdbview->Upgrade()) {
                     strLoadError =
                         _("Error upgrading chainstate database").translated;
                     break;
                 }
 
                 // ReplayBlocks is a no-op if we cleared the coinsviewdb with
                 // -reindex or -reindex-chainstate
                 if (!ReplayBlocks(params, pcoinsdbview.get())) {
                     strLoadError =
                         _("Unable to replay blocks. You will need to rebuild "
                           "the database using -reindex-chainstate.")
                             .translated;
                     break;
                 }
 
                 // The on-disk coinsdb is now in a good state, create the cache
                 pcoinsTip.reset(new CCoinsViewCache(pcoinscatcher.get()));
 
                 bool is_coinsview_empty = fReset || fReindexChainState ||
                                           pcoinsTip->GetBestBlock().IsNull();
                 if (!is_coinsview_empty) {
                     // LoadChainTip sets ::ChainActive() based on pcoinsTip's
                     // best block
                     if (!LoadChainTip(config)) {
                         strLoadError =
                             _("Error initializing block database").translated;
                         break;
                     }
                     assert(::ChainActive().Tip() != nullptr);
 
                     uiInterface.InitMessage(
                         _("Verifying blocks...").translated);
                     if (fHavePruned &&
                         gArgs.GetArg("-checkblocks", DEFAULT_CHECKBLOCKS) >
                             MIN_BLOCKS_TO_KEEP) {
                         LogPrintf(
                             "Prune: pruned datadir may not have more than %d "
                             "blocks; only checking available blocks\n",
                             MIN_BLOCKS_TO_KEEP);
                     }
 
                     CBlockIndex *tip = ::ChainActive().Tip();
                     RPCNotifyBlockChange(true, tip);
                     if (tip && tip->nTime >
                                    GetAdjustedTime() + MAX_FUTURE_BLOCK_TIME) {
                         strLoadError =
                             _("The block database contains a block which "
                               "appears to be from the future. This may be due "
                               "to your computer's date and time being set "
                               "incorrectly. Only rebuild the block database if "
                               "you are sure that your computer's date and time "
                               "are correct")
                                 .translated;
                         break;
                     }
 
                     if (!CVerifyDB().VerifyDB(
                             config, pcoinsdbview.get(),
                             gArgs.GetArg("-checklevel", DEFAULT_CHECKLEVEL),
                             gArgs.GetArg("-checkblocks",
                                          DEFAULT_CHECKBLOCKS))) {
                         strLoadError =
                             _("Corrupted block database detected").translated;
                         break;
                     }
                 }
             } catch (const std::exception &e) {
                 LogPrintf("%s\n", e.what());
                 strLoadError = _("Error opening block database").translated;
                 break;
             }
 
             fLoaded = true;
         } while (false);
 
         if (!fLoaded && !ShutdownRequested()) {
             // first suggest a reindex
             if (!fReset) {
                 bool fRet = uiInterface.ThreadSafeQuestion(
                     strLoadError + ".\n\n" +
                         _("Do you want to rebuild the block database now?")
                             .translated,
                     strLoadError + ".\nPlease restart with -reindex or "
                                    "-reindex-chainstate to recover.",
                     "",
                     CClientUIInterface::MSG_ERROR |
                         CClientUIInterface::BTN_ABORT);
                 if (fRet) {
                     fReindex = true;
                     AbortShutdown();
                 } else {
                     LogPrintf("Aborted block database rebuild. Exiting.\n");
                     return false;
                 }
             } else {
                 return InitError(strLoadError);
             }
         }
     }
 
     // As LoadBlockIndex can take several minutes, it's possible the user
     // requested to kill the GUI during the last operation. If so, exit.
     // As the program has not fully started yet, Shutdown() is possibly
     // overkill.
     if (ShutdownRequested()) {
         LogPrintf("Shutdown requested. Exiting.\n");
         return false;
     }
     if (fLoaded) {
         LogPrintf(" block index %15dms\n", GetTimeMillis() - nStart);
     }
 
     // Encoded addresses using cashaddr instead of base58.
     // We do this by default to avoid confusion with BTC addresses.
     config.SetCashAddrEncoding(gArgs.GetBoolArg("-usecashaddr", true));
 
     // Now that the chain state is loaded, make mempool generally available in
     // the node context. For example the connection manager, wallet, or RPC
     // threads, which are all started after this, may use it from the node
     // context.
     assert(!node.mempool);
     node.mempool = &::g_mempool;
 
     // Step 8: load indexers
     if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
         g_txindex = std::make_unique<TxIndex>(nTxIndexCache, false, fReindex);
         g_txindex->Start();
     }
 
     for (const auto &filter_type : g_enabled_filter_types) {
         InitBlockFilterIndex(filter_type, filter_index_cache, false, fReindex);
         GetBlockFilterIndex(filter_type)->Start();
     }
 
     // Step 9: load wallet
     for (const auto &client : node.chain_clients) {
         if (!client->load(chainparams)) {
             return false;
         }
     }
 
     // Step 10: data directory maintenance
 
     // if pruning, unset the service bit and perform the initial blockstore
     // prune after any wallet rescanning has taken place.
     if (fPruneMode) {
         LogPrintf("Unsetting NODE_NETWORK on prune mode\n");
         nLocalServices = ServiceFlags(nLocalServices & ~NODE_NETWORK);
         if (!fReindex) {
             uiInterface.InitMessage(_("Pruning blockstore...").translated);
             ::ChainstateActive().PruneAndFlush();
         }
     }
 
     // Step 11: import blocks
     if (!CheckDiskSpace(GetDataDir())) {
         InitError(strprintf(_("Error: Disk space is low for %s").translated,
                             GetDataDir()));
         return false;
     }
     if (!CheckDiskSpace(GetBlocksDir())) {
         InitError(strprintf(_("Error: Disk space is low for %s").translated,
                             GetBlocksDir()));
         return false;
     }
 
     // Either install a handler to notify us when genesis activates, or set
     // fHaveGenesis directly.
     // No locking, as this happens before any background thread is started.
     if (::ChainActive().Tip() == nullptr) {
         uiInterface.NotifyBlockTip_connect(BlockNotifyGenesisWait);
     } else {
         fHaveGenesis = true;
     }
 
     if (gArgs.IsArgSet("-blocknotify")) {
         uiInterface.NotifyBlockTip_connect(BlockNotifyCallback);
     }
 
     std::vector<fs::path> vImportFiles;
     for (const std::string &strFile : gArgs.GetArgs("-loadblock")) {
         vImportFiles.push_back(strFile);
     }
 
     threadGroup.create_thread(
         std::bind(&ThreadImport, std::ref(config), vImportFiles));
 
     // Wait for genesis block to be processed
     {
         WAIT_LOCK(g_genesis_wait_mutex, lock);
         // We previously could hang here if StartShutdown() is called prior to
         // ThreadImport getting started, so instead we just wait on a timer to
         // check ShutdownRequested() regularly.
         while (!fHaveGenesis && !ShutdownRequested()) {
             g_genesis_wait_cv.wait_for(lock, std::chrono::milliseconds(500));
         }
         uiInterface.NotifyBlockTip_disconnect(BlockNotifyGenesisWait);
     }
 
     if (ShutdownRequested()) {
         return false;
     }
 
     // Step 12: start node
 
     int chain_active_height;
 
     //// debug print
     {
         LOCK(cs_main);
         LogPrintf("mapBlockIndex.size() = %u\n", mapBlockIndex.size());
         chain_active_height = ::ChainActive().Height();
     }
     LogPrintf("nBestHeight = %d\n", chain_active_height);
 
     if (gArgs.GetBoolArg("-listenonion", DEFAULT_LISTEN_ONION)) {
         StartTorControl();
     }
 
     Discover();
 
     // Map ports with UPnP
     if (gArgs.GetBoolArg("-upnp", DEFAULT_UPNP)) {
         StartMapPort();
     }
 
     CConnman::Options connOptions;
     connOptions.nLocalServices = nLocalServices;
     connOptions.nMaxConnections = nMaxConnections;
     connOptions.m_max_outbound_full_relay = std::min(
         MAX_OUTBOUND_FULL_RELAY_CONNECTIONS, connOptions.nMaxConnections);
     connOptions.m_max_outbound_block_relay = std::min(
         MAX_BLOCKS_ONLY_CONNECTIONS,
         connOptions.nMaxConnections - connOptions.m_max_outbound_full_relay);
     connOptions.nMaxAddnode = MAX_ADDNODE_CONNECTIONS;
     connOptions.nMaxFeeler = 1;
     connOptions.nBestHeight = chain_active_height;
     connOptions.uiInterface = &uiInterface;
     connOptions.m_banman = node.banman.get();
     connOptions.m_msgproc = node.peer_logic.get();
     connOptions.nSendBufferMaxSize =
         1000 * gArgs.GetArg("-maxsendbuffer", DEFAULT_MAXSENDBUFFER);
     connOptions.nReceiveFloodSize =
         1000 * gArgs.GetArg("-maxreceivebuffer", DEFAULT_MAXRECEIVEBUFFER);
     connOptions.m_added_nodes = gArgs.GetArgs("-addnode");
 
     connOptions.nMaxOutboundTimeframe = nMaxOutboundTimeframe;
     connOptions.nMaxOutboundLimit = nMaxOutboundLimit;
     connOptions.m_peer_connect_timeout = peer_connect_timeout;
 
     for (const std::string &strBind : gArgs.GetArgs("-bind")) {
         CService addrBind;
         if (!Lookup(strBind.c_str(), addrBind, GetListenPort(), false)) {
             return InitError(ResolveErrMsg("bind", strBind));
         }
         connOptions.vBinds.push_back(addrBind);
     }
 
     for (const std::string &strBind : gArgs.GetArgs("-whitebind")) {
         NetWhitebindPermissions whitebind;
         std::string error;
         if (!NetWhitebindPermissions::TryParse(strBind, whitebind, error)) {
             return InitError(error);
         }
         connOptions.vWhiteBinds.push_back(whitebind);
     }
 
     for (const auto &net : gArgs.GetArgs("-whitelist")) {
         NetWhitelistPermissions subnet;
         std::string error;
         if (!NetWhitelistPermissions::TryParse(net, subnet, error)) {
             return InitError(error);
         }
         connOptions.vWhitelistedRange.push_back(subnet);
     }
 
     connOptions.vSeedNodes = gArgs.GetArgs("-seednode");
 
     // Initiate outbound connections unless connect=0
     connOptions.m_use_addrman_outgoing = !gArgs.IsArgSet("-connect");
     if (!connOptions.m_use_addrman_outgoing) {
         const auto connect = gArgs.GetArgs("-connect");
         if (connect.size() != 1 || connect[0] != "0") {
             connOptions.m_specified_outgoing = connect;
         }
     }
     if (!node.connman->Start(scheduler, connOptions)) {
         return false;
     }
 
     // Step 13: finished
 
     SetRPCWarmupFinished();
     uiInterface.InitMessage(_("Done loading").translated);
 
     for (const auto &client : node.chain_clients) {
         client->start(scheduler);
     }
 
     BanMan *banman = node.banman.get();
     scheduler.scheduleEvery(
         [banman] {
             banman->DumpBanlist();
             return true;
         },
         DUMP_BANS_INTERVAL * 1000);
 
     // Start Avalanche's event loop.
     g_avalanche->startEventLoop(scheduler);
 
     return true;
 }
diff --git a/src/zmq/zmqabstractnotifier.cpp b/src/zmq/zmqabstractnotifier.cpp
index 86bc6b80f..78de4afe6 100644
--- a/src/zmq/zmqabstractnotifier.cpp
+++ b/src/zmq/zmqabstractnotifier.cpp
@@ -1,18 +1,20 @@
 // Copyright (c) 2015 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <zmq/zmqabstractnotifier.h>
 
+const int CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM;
+
 CZMQAbstractNotifier::~CZMQAbstractNotifier() {
     assert(!psocket);
 }
 
 bool CZMQAbstractNotifier::NotifyBlock(const CBlockIndex * /*CBlockIndex*/) {
     return true;
 }
 
 bool CZMQAbstractNotifier::NotifyTransaction(
     const CTransaction & /*transaction*/) {
     return true;
 }
diff --git a/src/zmq/zmqabstractnotifier.h b/src/zmq/zmqabstractnotifier.h
index 0b658bc04..421ef452a 100644
--- a/src/zmq/zmqabstractnotifier.h
+++ b/src/zmq/zmqabstractnotifier.h
@@ -1,41 +1,54 @@
 // Copyright (c) 2015 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_ZMQ_ZMQABSTRACTNOTIFIER_H
 #define BITCOIN_ZMQ_ZMQABSTRACTNOTIFIER_H
 
 #include <zmq/zmqconfig.h>
 
 class CBlockIndex;
 class CZMQAbstractNotifier;
 
 typedef CZMQAbstractNotifier *(*CZMQNotifierFactory)();
 
 class CZMQAbstractNotifier {
 public:
-    CZMQAbstractNotifier() : psocket(nullptr) {}
+    static const int DEFAULT_ZMQ_SNDHWM{1000};
+
+    CZMQAbstractNotifier()
+        : psocket(nullptr),
+          outbound_message_high_water_mark(DEFAULT_ZMQ_SNDHWM) {}
     virtual ~CZMQAbstractNotifier();
 
     template <typename T> static CZMQAbstractNotifier *Create() {
         return new T();
     }
 
     std::string GetType() const { return type; }
     void SetType(const std::string &t) { type = t; }
     std::string GetAddress() const { return address; }
     void SetAddress(const std::string &a) { address = a; }
+    int GetOutboundMessageHighWaterMark() const {
+        return outbound_message_high_water_mark;
+    }
+    void SetOutboundMessageHighWaterMark(const int sndhwm) {
+        if (sndhwm >= 0) {
+            outbound_message_high_water_mark = sndhwm;
+        }
+    }
 
     virtual bool Initialize(void *pcontext) = 0;
     virtual void Shutdown() = 0;
 
     virtual bool NotifyBlock(const CBlockIndex *pindex);
     virtual bool NotifyTransaction(const CTransaction &transaction);
 
 protected:
     void *psocket;
     std::string type;
     std::string address;
+    int outbound_message_high_water_mark; // aka SNDHWM
 };
 
 #endif // BITCOIN_ZMQ_ZMQABSTRACTNOTIFIER_H
diff --git a/src/zmq/zmqnotificationinterface.cpp b/src/zmq/zmqnotificationinterface.cpp
index 9031477dd..e336ea34e 100644
--- a/src/zmq/zmqnotificationinterface.cpp
+++ b/src/zmq/zmqnotificationinterface.cpp
@@ -1,186 +1,189 @@
 // Copyright (c) 2015-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <zmq/zmqnotificationinterface.h>
 #include <zmq/zmqpublishnotifier.h>
 
 #include <util/system.h>
 #include <validation.h>
 #include <version.h>
 
 void zmqError(const char *str) {
     LogPrint(BCLog::ZMQ, "zmq: Error: %s, errno=%s\n", str,
              zmq_strerror(errno));
 }
 
 CZMQNotificationInterface::CZMQNotificationInterface() : pcontext(nullptr) {}
 
 CZMQNotificationInterface::~CZMQNotificationInterface() {
     Shutdown();
 
     for (std::list<CZMQAbstractNotifier *>::iterator i = notifiers.begin();
          i != notifiers.end(); ++i) {
         delete *i;
     }
 }
 
 std::list<const CZMQAbstractNotifier *>
 CZMQNotificationInterface::GetActiveNotifiers() const {
     std::list<const CZMQAbstractNotifier *> result;
     for (const auto *n : notifiers) {
         result.push_back(n);
     }
     return result;
 }
 
 CZMQNotificationInterface *CZMQNotificationInterface::Create() {
     CZMQNotificationInterface *notificationInterface = nullptr;
     std::map<std::string, CZMQNotifierFactory> factories;
     std::list<CZMQAbstractNotifier *> notifiers;
 
     factories["pubhashblock"] =
         CZMQAbstractNotifier::Create<CZMQPublishHashBlockNotifier>;
     factories["pubhashtx"] =
         CZMQAbstractNotifier::Create<CZMQPublishHashTransactionNotifier>;
     factories["pubrawblock"] =
         CZMQAbstractNotifier::Create<CZMQPublishRawBlockNotifier>;
     factories["pubrawtx"] =
         CZMQAbstractNotifier::Create<CZMQPublishRawTransactionNotifier>;
 
     for (const auto &entry : factories) {
         std::string arg("-zmq" + entry.first);
         if (gArgs.IsArgSet(arg)) {
             CZMQNotifierFactory factory = entry.second;
             std::string address = gArgs.GetArg(arg, "");
             CZMQAbstractNotifier *notifier = factory();
             notifier->SetType(entry.first);
             notifier->SetAddress(address);
+            notifier->SetOutboundMessageHighWaterMark(
+                static_cast<int>(gArgs.GetArg(
+                    arg + "hwm", CZMQAbstractNotifier::DEFAULT_ZMQ_SNDHWM)));
             notifiers.push_back(notifier);
         }
     }
 
     if (!notifiers.empty()) {
         notificationInterface = new CZMQNotificationInterface();
         notificationInterface->notifiers = notifiers;
 
         if (!notificationInterface->Initialize()) {
             delete notificationInterface;
             notificationInterface = nullptr;
         }
     }
 
     return notificationInterface;
 }
 
 // Called at startup to conditionally set up ZMQ socket(s)
 bool CZMQNotificationInterface::Initialize() {
     int major = 0, minor = 0, patch = 0;
     zmq_version(&major, &minor, &patch);
     LogPrint(BCLog::ZMQ, "zmq: version %d.%d.%d\n", major, minor, patch);
 
     LogPrint(BCLog::ZMQ, "zmq: Initialize notification interface\n");
     assert(!pcontext);
 
     pcontext = zmq_ctx_new();
 
     if (!pcontext) {
         zmqError("Unable to initialize context");
         return false;
     }
 
     std::list<CZMQAbstractNotifier *>::iterator i = notifiers.begin();
     for (; i != notifiers.end(); ++i) {
         CZMQAbstractNotifier *notifier = *i;
         if (notifier->Initialize(pcontext)) {
-            LogPrint(BCLog::ZMQ, "  Notifier %s ready (address = %s)\n",
+            LogPrint(BCLog::ZMQ, "zmq: Notifier %s ready (address = %s)\n",
                      notifier->GetType(), notifier->GetAddress());
         } else {
-            LogPrint(BCLog::ZMQ, "  Notifier %s failed (address = %s)\n",
+            LogPrint(BCLog::ZMQ, "zmq: Notifier %s failed (address = %s)\n",
                      notifier->GetType(), notifier->GetAddress());
             break;
         }
     }
 
     if (i != notifiers.end()) {
         return false;
     }
 
     return true;
 }
 
 // Called during shutdown sequence
 void CZMQNotificationInterface::Shutdown() {
     LogPrint(BCLog::ZMQ, "zmq: Shutdown notification interface\n");
     if (pcontext) {
         for (std::list<CZMQAbstractNotifier *>::iterator i = notifiers.begin();
              i != notifiers.end(); ++i) {
             CZMQAbstractNotifier *notifier = *i;
-            LogPrint(BCLog::ZMQ, "   Shutdown notifier %s at %s\n",
+            LogPrint(BCLog::ZMQ, "zmq: Shutdown notifier %s at %s\n",
                      notifier->GetType(), notifier->GetAddress());
             notifier->Shutdown();
         }
         zmq_ctx_term(pcontext);
 
         pcontext = nullptr;
     }
 }
 
 void CZMQNotificationInterface::UpdatedBlockTip(const CBlockIndex *pindexNew,
                                                 const CBlockIndex *pindexFork,
                                                 bool fInitialDownload) {
     // In IBD or blocks were disconnected without any new ones
     if (fInitialDownload || pindexNew == pindexFork) {
         return;
     }
 
     for (std::list<CZMQAbstractNotifier *>::iterator i = notifiers.begin();
          i != notifiers.end();) {
         CZMQAbstractNotifier *notifier = *i;
         if (notifier->NotifyBlock(pindexNew)) {
             i++;
         } else {
             notifier->Shutdown();
             i = notifiers.erase(i);
         }
     }
 }
 
 void CZMQNotificationInterface::TransactionAddedToMempool(
     const CTransactionRef &ptx) {
     // Used by BlockConnected and BlockDisconnected as well, because they're all
     // the same external callback.
     const CTransaction &tx = *ptx;
 
     for (std::list<CZMQAbstractNotifier *>::iterator i = notifiers.begin();
          i != notifiers.end();) {
         CZMQAbstractNotifier *notifier = *i;
         if (notifier->NotifyTransaction(tx)) {
             i++;
         } else {
             notifier->Shutdown();
             i = notifiers.erase(i);
         }
     }
 }
 
 void CZMQNotificationInterface::BlockConnected(
     const std::shared_ptr<const CBlock> &pblock,
     const CBlockIndex *pindexConnected,
     const std::vector<CTransactionRef> &vtxConflicted) {
     for (const CTransactionRef &ptx : pblock->vtx) {
         // Do a normal notify for each transaction added in the block
         TransactionAddedToMempool(ptx);
     }
 }
 
 void CZMQNotificationInterface::BlockDisconnected(
     const std::shared_ptr<const CBlock> &pblock) {
     for (const CTransactionRef &ptx : pblock->vtx) {
         // Do a normal notify for each transaction removed in block
         // disconnection
         TransactionAddedToMempool(ptx);
     }
 }
 
 CZMQNotificationInterface *g_zmq_notification_interface = nullptr;
diff --git a/src/zmq/zmqpublishnotifier.cpp b/src/zmq/zmqpublishnotifier.cpp
index 129347abc..81a4196d4 100644
--- a/src/zmq/zmqpublishnotifier.cpp
+++ b/src/zmq/zmqpublishnotifier.cpp
@@ -1,198 +1,211 @@
 // Copyright (c) 2015-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <zmq/zmqpublishnotifier.h>
 
 #include <chain.h>
 #include <chainparams.h>
 #include <config.h>
 #include <primitives/blockhash.h>
 #include <primitives/txid.h>
 #include <rpc/server.h>
 #include <streams.h>
 #include <util/system.h>
 #include <validation.h>
 
 #include <cstdarg>
 
 static std::multimap<std::string, CZMQAbstractPublishNotifier *>
     mapPublishNotifiers;
 
 static const char *MSG_HASHBLOCK = "hashblock";
 static const char *MSG_HASHTX = "hashtx";
 static const char *MSG_RAWBLOCK = "rawblock";
 static const char *MSG_RAWTX = "rawtx";
 
 // Internal function to send multipart message
 static int zmq_send_multipart(void *sock, const void *data, size_t size, ...) {
     va_list args;
     va_start(args, size);
 
     while (1) {
         zmq_msg_t msg;
 
         int rc = zmq_msg_init_size(&msg, size);
         if (rc != 0) {
             zmqError("Unable to initialize ZMQ msg");
             va_end(args);
             return -1;
         }
 
         void *buf = zmq_msg_data(&msg);
         memcpy(buf, data, size);
 
         data = va_arg(args, const void *);
 
         rc = zmq_msg_send(&msg, sock, data ? ZMQ_SNDMORE : 0);
         if (rc == -1) {
             zmqError("Unable to send ZMQ msg");
             zmq_msg_close(&msg);
             va_end(args);
             return -1;
         }
 
         zmq_msg_close(&msg);
 
         if (!data) {
             break;
         }
 
         size = va_arg(args, size_t);
     }
     va_end(args);
     return 0;
 }
 
 bool CZMQAbstractPublishNotifier::Initialize(void *pcontext) {
     assert(!psocket);
 
     // check if address is being used by other publish notifier
     std::multimap<std::string, CZMQAbstractPublishNotifier *>::iterator i =
         mapPublishNotifiers.find(address);
 
     if (i == mapPublishNotifiers.end()) {
         psocket = zmq_socket(pcontext, ZMQ_PUB);
         if (!psocket) {
             zmqError("Failed to create socket");
             return false;
         }
 
-        int rc = zmq_bind(psocket, address.c_str());
+        LogPrint(BCLog::ZMQ,
+                 "zmq: Outbound message high water mark for %s at %s is %d\n",
+                 type, address, outbound_message_high_water_mark);
+
+        int rc = zmq_setsockopt(psocket, ZMQ_SNDHWM,
+                                &outbound_message_high_water_mark,
+                                sizeof(outbound_message_high_water_mark));
+        if (rc != 0) {
+            zmqError("Failed to set outbound message high water mark");
+            zmq_close(psocket);
+            return false;
+        }
+
+        rc = zmq_bind(psocket, address.c_str());
         if (rc != 0) {
             zmqError("Failed to bind address");
             zmq_close(psocket);
             return false;
         }
 
         // register this notifier for the address, so it can be reused for other
         // publish notifier
         mapPublishNotifiers.insert(std::make_pair(address, this));
         return true;
     } else {
         LogPrint(BCLog::ZMQ, "zmq: Reusing socket for address %s\n", address);
 
         psocket = i->second->psocket;
         mapPublishNotifiers.insert(std::make_pair(address, this));
 
         return true;
     }
 }
 
 void CZMQAbstractPublishNotifier::Shutdown() {
     assert(psocket);
 
     int count = mapPublishNotifiers.count(address);
 
     // remove this notifier from the list of publishers using this address
     typedef std::multimap<std::string, CZMQAbstractPublishNotifier *>::iterator
         iterator;
     std::pair<iterator, iterator> iterpair =
         mapPublishNotifiers.equal_range(address);
 
     for (iterator it = iterpair.first; it != iterpair.second; ++it) {
         if (it->second == this) {
             mapPublishNotifiers.erase(it);
             break;
         }
     }
 
     if (count == 1) {
-        LogPrint(BCLog::ZMQ, "Close socket at address %s\n", address);
+        LogPrint(BCLog::ZMQ, "zmq: Close socket at address %s\n", address);
         int linger = 0;
         zmq_setsockopt(psocket, ZMQ_LINGER, &linger, sizeof(linger));
         zmq_close(psocket);
     }
 
     psocket = nullptr;
 }
 
 bool CZMQAbstractPublishNotifier::SendMessage(const char *command,
                                               const void *data, size_t size) {
     assert(psocket);
 
     /* send three parts, command & data & a LE 4byte sequence number */
     uint8_t msgseq[sizeof(uint32_t)];
     WriteLE32(&msgseq[0], nSequence);
     int rc = zmq_send_multipart(psocket, command, strlen(command), data, size,
                                 msgseq, (size_t)sizeof(uint32_t), nullptr);
     if (rc == -1) {
         return false;
     }
 
     /* increment memory only sequence number after sending */
     nSequence++;
 
     return true;
 }
 
 bool CZMQPublishHashBlockNotifier::NotifyBlock(const CBlockIndex *pindex) {
     BlockHash hash = pindex->GetBlockHash();
     LogPrint(BCLog::ZMQ, "zmq: Publish hashblock %s\n", hash.GetHex());
     char data[32];
     for (unsigned int i = 0; i < 32; i++) {
         data[31 - i] = hash.begin()[i];
     }
     return SendMessage(MSG_HASHBLOCK, data, 32);
 }
 
 bool CZMQPublishHashTransactionNotifier::NotifyTransaction(
     const CTransaction &transaction) {
     TxId txid = transaction.GetId();
     LogPrint(BCLog::ZMQ, "zmq: Publish hashtx %s\n", txid.GetHex());
     char data[32];
     for (unsigned int i = 0; i < 32; i++) {
         data[31 - i] = txid.begin()[i];
     }
     return SendMessage(MSG_HASHTX, data, 32);
 }
 
 bool CZMQPublishRawBlockNotifier::NotifyBlock(const CBlockIndex *pindex) {
     LogPrint(BCLog::ZMQ, "zmq: Publish rawblock %s\n",
              pindex->GetBlockHash().GetHex());
 
     const Config &config = GetConfig();
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION | RPCSerializationFlags());
     {
         LOCK(cs_main);
         CBlock block;
         if (!ReadBlockFromDisk(block, pindex,
                                config.GetChainParams().GetConsensus())) {
             zmqError("Can't read block from disk");
             return false;
         }
 
         ss << block;
     }
 
     return SendMessage(MSG_RAWBLOCK, &(*ss.begin()), ss.size());
 }
 
 bool CZMQPublishRawTransactionNotifier::NotifyTransaction(
     const CTransaction &transaction) {
     TxId txid = transaction.GetId();
     LogPrint(BCLog::ZMQ, "zmq: Publish rawtx %s\n", txid.GetHex());
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION | RPCSerializationFlags());
     ss << transaction;
     return SendMessage(MSG_RAWTX, &(*ss.begin()), ss.size());
 }
diff --git a/src/zmq/zmqpublishnotifier.h b/src/zmq/zmqpublishnotifier.h
index 2aad88368..4b6c98389 100644
--- a/src/zmq/zmqpublishnotifier.h
+++ b/src/zmq/zmqpublishnotifier.h
@@ -1,50 +1,50 @@
 // Copyright (c) 2015-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_ZMQ_ZMQPUBLISHNOTIFIER_H
 #define BITCOIN_ZMQ_ZMQPUBLISHNOTIFIER_H
 
 #include <zmq/zmqabstractnotifier.h>
 
 class CBlockIndex;
 
 class CZMQAbstractPublishNotifier : public CZMQAbstractNotifier {
 private:
     //! upcounting per message sequence number
-    uint32_t nSequence;
+    uint32_t nSequence{0U};
 
 public:
     /* send zmq multipart message
        parts:
           * command
           * data
           * message sequence number
     */
     bool SendMessage(const char *command, const void *data, size_t size);
 
     bool Initialize(void *pcontext) override;
     void Shutdown() override;
 };
 
 class CZMQPublishHashBlockNotifier : public CZMQAbstractPublishNotifier {
 public:
     bool NotifyBlock(const CBlockIndex *pindex) override;
 };
 
 class CZMQPublishHashTransactionNotifier : public CZMQAbstractPublishNotifier {
 public:
     bool NotifyTransaction(const CTransaction &transaction) override;
 };
 
 class CZMQPublishRawBlockNotifier : public CZMQAbstractPublishNotifier {
 public:
     bool NotifyBlock(const CBlockIndex *pindex) override;
 };
 
 class CZMQPublishRawTransactionNotifier : public CZMQAbstractPublishNotifier {
 public:
     bool NotifyTransaction(const CTransaction &transaction) override;
 };
 
 #endif // BITCOIN_ZMQ_ZMQPUBLISHNOTIFIER_H
diff --git a/src/zmq/zmqrpc.cpp b/src/zmq/zmqrpc.cpp
index daf9b22f3..ea1954cc6 100644
--- a/src/zmq/zmqrpc.cpp
+++ b/src/zmq/zmqrpc.cpp
@@ -1,67 +1,70 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <zmq/zmqrpc.h>
 
 #include <rpc/server.h>
 #include <rpc/util.h>
 #include <zmq/zmqabstractnotifier.h>
 #include <zmq/zmqnotificationinterface.h>
 
 #include <univalue.h>
 
 namespace {
 
 UniValue getzmqnotifications(const Config &config,
                              const JSONRPCRequest &request) {
     if (request.fHelp || request.params.size() != 0) {
         throw std::runtime_error(RPCHelpMan{
             "getzmqnotifications",
             "\nReturns information about the active ZeroMQ "
             "notifications.\n",
             {},
             RPCResult{
                 "[\n"
                 "  {                        (json object)\n"
                 "    \"type\": \"pubhashtx\",   (string) Type of notification\n"
                 "    \"address\": \"...\"       (string) Address of the "
                 "publisher\n"
+                "    \"hwm\": n               (numeric) Outbound message high "
+                "water mark\n"
                 "  },\n"
                 "  ...\n"
                 "]\n"},
             RPCExamples{HelpExampleCli("getzmqnotifications", "") +
                         HelpExampleRpc("getzmqnotifications", "")},
         }
                                      .ToString());
     }
 
     UniValue result(UniValue::VARR);
     if (g_zmq_notification_interface != nullptr) {
         for (const auto *n :
              g_zmq_notification_interface->GetActiveNotifiers()) {
             UniValue obj(UniValue::VOBJ);
             obj.pushKV("type", n->GetType());
             obj.pushKV("address", n->GetAddress());
+            obj.pushKV("hwm", n->GetOutboundMessageHighWaterMark());
             result.push_back(obj);
         }
     }
 
     return result;
 }
 
 // clang-format off
 static const CRPCCommand commands[] = {
     //  category          name                     actor (function)        argNames
     //  ----------------- ------------------------ ----------------------- ----------
     { "zmq",            "getzmqnotifications",   getzmqnotifications,    {} },
 };
 // clang-format on
 
 } // anonymous namespace
 
 void RegisterZMQRPCCommands(CRPCTable &t) {
     for (const auto &c : commands) {
         t.appendCommand(c.name, &c);
     }
 }
diff --git a/test/functional/interface_zmq.py b/test/functional/interface_zmq.py
index a13b69603..d5bf095c1 100755
--- a/test/functional/interface_zmq.py
+++ b/test/functional/interface_zmq.py
@@ -1,138 +1,138 @@
 #!/usr/bin/env python3
 # Copyright (c) 2015-2019 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the ZMQ notification interface."""
 import struct
 from io import BytesIO
 
 from test_framework.address import ADDRESS_BCHREG_UNSPENDABLE
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.messages import CTransaction
 from test_framework.util import (
     assert_equal,
     hash256,
 )
 
 ADDRESS = "tcp://127.0.0.1:28332"
 
 
 class ZMQSubscriber:
     def __init__(self, socket, topic):
         self.sequence = 0
         self.socket = socket
         self.topic = topic
 
         import zmq
         self.socket.setsockopt(zmq.SUBSCRIBE, self.topic)
 
     def receive(self):
         topic, body, seq = self.socket.recv_multipart()
         # Topic should match the subscriber topic.
         assert_equal(topic, self.topic)
         # Sequence should be incremental.
         assert_equal(struct.unpack('<I', seq)[-1], self.sequence)
         self.sequence += 1
         return body
 
 
 class ZMQTest (BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 2
 
     def skip_test_if_missing_module(self):
         self.skip_if_no_py3_zmq()
         self.skip_if_no_bitcoind_zmq()
 
     def setup_nodes(self):
         import zmq
 
         # Initialize ZMQ context and socket.
         # All messages are received in the same socket which means that this
         # test fails if the publishing order changes.
         # Note that the publishing order is not defined in the documentation and
         # is subject to change.
         self.zmq_context = zmq.Context()
         socket = self.zmq_context.socket(zmq.SUB)
         socket.set(zmq.RCVTIMEO, 60000)
         socket.connect(ADDRESS)
 
         # Subscribe to all available topics.
         self.hashblock = ZMQSubscriber(socket, b"hashblock")
         self.hashtx = ZMQSubscriber(socket, b"hashtx")
         self.rawblock = ZMQSubscriber(socket, b"rawblock")
         self.rawtx = ZMQSubscriber(socket, b"rawtx")
 
         self.extra_args = [
             ["-zmqpub{}={}".format(sub.topic.decode(), ADDRESS) for sub in [
                 self.hashblock, self.hashtx, self.rawblock, self.rawtx]],
             [],
         ]
         self.add_nodes(self.num_nodes, self.extra_args)
         self.start_nodes()
         self.import_deterministic_coinbase_privkeys()
 
     def run_test(self):
         try:
             self._zmq_test()
         finally:
             # Destroy the ZMQ context.
             self.log.debug("Destroying ZMQ context")
             self.zmq_context.destroy(linger=None)
 
     def _zmq_test(self):
         num_blocks = 5
         self.log.info(
             "Generate {0} blocks (and {0} coinbase txes)".format(num_blocks))
         genhashes = self.nodes[0].generatetoaddress(
             num_blocks, ADDRESS_BCHREG_UNSPENDABLE)
         self.sync_all()
 
         for x in range(num_blocks):
             # Should receive the coinbase txid.
             txid = self.hashtx.receive()
 
             # Should receive the coinbase raw transaction.
             hex = self.rawtx.receive()
             tx = CTransaction()
             tx.deserialize(BytesIO(hex))
             tx.calc_sha256()
             assert_equal(tx.hash, txid.hex())
 
             # Should receive the generated block hash.
             hash = self.hashblock.receive().hex()
             assert_equal(genhashes[x], hash)
             # The block should only have the coinbase txid.
             assert_equal([txid.hex()], self.nodes[1].getblock(hash)["tx"])
 
             # Should receive the generated raw block.
             block = self.rawblock.receive()
             assert_equal(genhashes[x], hash256(block[:80]).hex())
 
         if self.is_wallet_compiled():
             self.log.info("Wait for tx from second node")
             payment_txid = self.nodes[1].sendtoaddress(
                 self.nodes[0].getnewaddress(), 1.0)
             self.sync_all()
 
             # Should receive the broadcasted txid.
             txid = self.hashtx.receive()
             assert_equal(payment_txid, txid.hex())
 
             # Should receive the broadcasted raw transaction.
             hex = self.rawtx.receive()
             assert_equal(payment_txid, hash256(hex).hex())
 
         self.log.info("Test the getzmqnotifications RPC")
         assert_equal(self.nodes[0].getzmqnotifications(), [
-            {"type": "pubhashblock", "address": ADDRESS},
-            {"type": "pubhashtx", "address": ADDRESS},
-            {"type": "pubrawblock", "address": ADDRESS},
-            {"type": "pubrawtx", "address": ADDRESS},
+            {"type": "pubhashblock", "address": ADDRESS, "hwm": 1000},
+            {"type": "pubhashtx", "address": ADDRESS, "hwm": 1000},
+            {"type": "pubrawblock", "address": ADDRESS, "hwm": 1000},
+            {"type": "pubrawtx", "address": ADDRESS, "hwm": 1000},
         ])
 
         assert_equal(self.nodes[1].getzmqnotifications(), [])
 
 
 if __name__ == '__main__':
     ZMQTest().main()
diff --git a/test/lint/check-doc.py b/test/lint/check-doc.py
index dec725cad..53f6e8b07 100755
--- a/test/lint/check-doc.py
+++ b/test/lint/check-doc.py
@@ -1,87 +1,92 @@
 #!/usr/bin/env python3
 # Copyright (c) 2015-2019 The Bitcoin Core developers
 # Copyright (c) 2019 The Bitcoin developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 '''
 This checks if all command line args are documented.
 Return value is 0 to indicate no error.
 
 Author: @MarcoFalke
 '''
 
 from subprocess import check_output
 from pprint import PrettyPrinter
 import glob
 import re
 
 TOP_LEVEL = 'git rev-parse --show-toplevel'
 FOLDER_SRC = '/src/**/'
 FOLDER_TEST = '/src/**/test/'
 
 EXTENSIONS = ["*.c", "*.h", "*.cpp", "*.cc", "*.hpp"]
 REGEX_ARG = r'(?:ForceSet|SoftSet|Get|Is)(?:Bool)?Args?(?:Set)?\(\s*"(-[^"]+)"'
 REGEX_DOC = r'AddArg\(\s*"(-[^"=]+?)(?:=|")'
 
 # list false positive unknows arguments
 SET_FALSE_POSITIVE_UNKNOWNS = set([
     '-includeconf',
     '-regtest',
     '-testnet',
     '-zmqpubhashblock',
     '-zmqpubhashtx',
     '-zmqpubrawblock',
     '-zmqpubrawtx',
+    '-zmqpubhashblockhwm',
+    '-zmqpubhashtxhwm',
+    '-zmqpubrawblockhwm',
+    '-zmqpubrawtxhwm',
+
 ])
 
 # list false positive undocumented arguments
 SET_FALSE_POSITIVE_UNDOCUMENTED = set(['-dbcrashratio',
                                        '-enableminerfund',
                                        '-forcecompactdb',
                                        '-parkdeepreorg',
                                        '-automaticunparking',
                                        # Remove after May 2020 upgrade
                                        '-phononactivationtime',
                                        '-replayprotectionactivationtime',
                                        ])
 
 
 def main():
     top_level = check_output(TOP_LEVEL, shell=True,
                              universal_newlines=True, encoding='utf8').strip()
     source_files = []
     test_files = []
 
     for extension in EXTENSIONS:
         source_files += glob.glob(top_level +
                                   FOLDER_SRC + extension, recursive=True)
         test_files += glob.glob(top_level + FOLDER_TEST +
                                 extension, recursive=True)
 
     files = set(source_files) - set(test_files)
 
     args_used = set()
     args_docd = set()
     for file in files:
         with open(file, 'r', encoding='utf-8') as f:
             content = f.read()
             args_used |= set(re.findall(re.compile(REGEX_ARG), content))
             args_docd |= set(re.findall(re.compile(REGEX_DOC), content))
 
     args_used |= SET_FALSE_POSITIVE_UNKNOWNS
     args_docd |= SET_FALSE_POSITIVE_UNDOCUMENTED
     args_need_doc = args_used - args_docd
     args_unknown = args_docd - args_used
 
     pp = PrettyPrinter()
     print("Args used        : {}".format(len(args_used)))
     print("Args documented  : {}".format(len(args_docd)))
     print("Args undocumented: {}".format(len(args_need_doc)))
     pp.pprint(args_need_doc)
     print("Args unknown     : {}".format(len(args_unknown)))
     pp.pprint(args_unknown)
 
 
 if __name__ == "__main__":
     main()