init.cpp:1635 prints mapBlockIndex.size() without cs_main. This is technically a race (though it is rather inconsequential). At some point someone should fix this so tsan stops complaining.
#else
    strUsage += HelpMessageOpt("-upnp", strprintf(_("Use UPnP to map the listening port (default: %u)"), 0));
#endif
#endif
    strUsage += HelpMessageOpt("-whitebind=<addr>", _("Bind to given address and whitelist peers connecting to it. Use [host]:port notation for IPv6"));
    strUsage += HelpMessageOpt("-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"));
    strUsage += HelpMessageOpt("-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));
#ifdef ENABLE_WALLET
    strUsage += CWallet::GetWalletHelpString(showDebug);
#endif
#if ENABLE_ZMQ
    strUsage += HelpMessageGroup(_("ZeroMQ notification options:"));
    strUsage += HelpMessageOpt("-zmqpubhashblock=<address>", _("Enable publish hash block in <address>"));
    strUsage += HelpMessageOpt("-zmqpubhashtx=<address>", _("Enable publish hash transaction in <address>"));
    strUsage += HelpMessageOpt("-zmqpubrawblock=<address>", _("Enable publish raw block in <address>"));
    strUsage += HelpMessageOpt("-zmqpubrawtx=<address>", _("Enable publish raw transaction in <address>"));
#endif
    strUsage += HelpMessageGroup(_("Debugging/Testing options:"));
    strUsage += HelpMessageOpt("-uacomment=<cmt>", _("Append comment to the user agent string"));
    if (showDebug)
    {
        strUsage += HelpMessageOpt("-checkblocks=<n>", strprintf(_("How many blocks to check at startup (default: %u, 0 = all)"), DEFAULT_CHECKBLOCKS));
        strUsage += HelpMessageOpt("-checklevel=<n>", strprintf(_("How thorough the block verification of -checkblocks is (0-4, default: %u)"), DEFAULT_CHECKLEVEL));
        strUsage += HelpMessageOpt("-checkblockindex", strprintf("Do a full consistency check for mapBlockIndex, setBlockIndexCandidates, chainActive and mapBlocksUnlinked occasionally. Also sets -checkmempool (default: %u)", defaultChainParams->DefaultConsistencyChecks()));
        strUsage += HelpMessageOpt("-checkmempool=<n>", strprintf("Run checks every <n> transactions (default: %u)", defaultChainParams->DefaultConsistencyChecks()));
        strUsage += HelpMessageOpt("-checkpoints", strprintf("Disable expensive verification for known chain history (default: %u)", DEFAULT_CHECKPOINTS_ENABLED));
        strUsage += HelpMessageOpt("-disablesafemode", strprintf("Disable safemode, override a real safe mode event (default: %u)", DEFAULT_DISABLE_SAFEMODE));
        strUsage += HelpMessageOpt("-testsafemode", strprintf("Force safe mode (default: %u)", DEFAULT_TESTSAFEMODE));
        strUsage += HelpMessageOpt("-dropmessagestest=<n>", "Randomly drop 1 of every <n> network messages");