From 99d6a1e86564d7b316a7de1d3565980811e650ce Mon Sep 17 00:00:00 2001
From: James O'Beirne <james.obeirne@gmail.com>
Date: Mon, 21 May 2018 13:44:23 -0400
Subject: [PATCH 1/5] disable thread_local on unreliable platforms

See discussions here:

- https://github.com/bitcoin/bitcoin/pull/11722#pullrequestreview-79322658
- https://github.com/bitcoin/bitcoin/pull/13168#issuecomment-387181155
---
 configure.ac | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 490b638ee1047..5138b8066e443 100644
--- a/configure.ac
+++ b/configure.ac
@@ -775,8 +775,23 @@ AC_LINK_IFELSE([AC_LANG_SOURCE([
   }
   ])],
   [
-    AC_DEFINE(HAVE_THREAD_LOCAL,1,[Define if thread_local is supported.])
-    AC_MSG_RESULT(yes)
+   case $host in
+     *mingw*)
+        # mingw32's implementation of thread_local has also been shown to behave
+        # erroneously under concurrent usage; see:
+        # https://gist.github.com/jamesob/fe9a872051a88b2025b1aa37bfa98605
+        AC_MSG_RESULT(no)
+        ;;
+      *darwin*)
+        # TODO enable thread_local on later versions of Darwin where it is
+        # supported (per https://stackoverflow.com/a/29929949)
+        AC_MSG_RESULT(no)
+        ;;
+      *)
+        AC_DEFINE(HAVE_THREAD_LOCAL,1,[Define if thread_local is supported.])
+        AC_MSG_RESULT(yes)
+        ;;
+    esac
   ],
   [
     AC_MSG_RESULT(no)

From 6e12f01b8480a93dcd97c08618e1c7c827ea72b7 Mon Sep 17 00:00:00 2001
From: James O'Beirne <james.obeirne@gmail.com>
Date: Wed, 13 Jun 2018 14:50:59 -0400
Subject: [PATCH 2/5] threads: introduce threadutil, refactor thread naming

This work is prerequisite to attaching thread names to log lines and deadlock
debug utilities. threadutil allows setting of an "internal" threadname per
thread on platforms where thread_local is available.

This commit also moves RenameThread() out of util and adds a numeric suffix to
disambiguate between threads with the same name. It explicitly names a few
main threads using the new Rename() utility.
---
 src/Makefile.am           |  2 ++
 src/bitcoind.cpp          |  3 ++
 src/httpserver.cpp        | 11 +++---
 src/init.cpp              |  7 ++--
 src/qt/bitcoin.cpp        |  3 ++
 src/test/test_bitcoin.cpp |  2 +-
 src/threadutil.cpp        | 76 +++++++++++++++++++++++++++++++++++++++
 src/threadutil.h          | 26 ++++++++++++++
 src/util.cpp              | 20 -----------
 src/util.h                |  6 ++--
 src/validation.cpp        |  5 +--
 src/validation.h          |  8 ++---
 12 files changed, 130 insertions(+), 39 deletions(-)
 create mode 100644 src/threadutil.cpp
 create mode 100644 src/threadutil.h

diff --git a/src/Makefile.am b/src/Makefile.am
index 458721293ebde..a0ab13e6e7cbc 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -169,6 +169,7 @@ BITCOIN_CORE_H = \
   support/events.h \
   support/lockedpool.h \
   sync.h \
+  threadutil.h \
   threadsafety.h \
   threadinterrupt.h \
   timedata.h \
@@ -409,6 +410,7 @@ libbitcoin_util_a_SOURCES = \
   rpc/protocol.cpp \
   support/cleanse.cpp \
   sync.cpp \
+  threadutil.cpp \
   threadinterrupt.cpp \
   util.cpp \
   utilmoneystr.cpp \
diff --git a/src/bitcoind.cpp b/src/bitcoind.cpp
index 494a925a79ac8..bf0268997cbfc 100644
--- a/src/bitcoind.cpp
+++ b/src/bitcoind.cpp
@@ -18,6 +18,7 @@
 #include <util.h>
 #include <httpserver.h>
 #include <httprpc.h>
+#include <threadutil.h>
 #include <utilstrencodings.h>
 #include <walletinitinterface.h>
 
@@ -58,6 +59,8 @@ static bool AppInit(int argc, char* argv[])
 {
     bool fRet = false;
 
+    thread_util::Rename("init");
+
     //
     // Parameters
     //
diff --git a/src/httpserver.cpp b/src/httpserver.cpp
index bd08b04c0f4af..229ff860ad1af 100644
--- a/src/httpserver.cpp
+++ b/src/httpserver.cpp
@@ -6,6 +6,7 @@
 
 #include <chainparamsbase.h>
 #include <compat.h>
+#include <threadutil.h>
 #include <util.h>
 #include <utilstrencodings.h>
 #include <netbase.h>
@@ -16,7 +17,7 @@
 #include <memory>
 #include <stdio.h>
 #include <stdlib.h>
-#include <string.h>
+#include <string>
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -281,7 +282,7 @@ static void http_reject_request_cb(struct evhttp_request* req, void*)
 /** Event dispatcher thread */
 static bool ThreadHTTP(struct event_base* base, struct evhttp* http)
 {
-    RenameThread("bitcoin-http");
+    thread_util::Rename("http");
     LogPrint(BCLog::HTTP, "Entering http event loop\n");
     event_base_dispatch(base);
     // Event loop will be interrupted by InterruptHTTPServer()
@@ -328,9 +329,9 @@ static bool HTTPBindAddresses(struct evhttp* http)
 }
 
 /** Simple wrapper to set thread name and run work queue */
-static void HTTPWorkQueueRun(WorkQueue<HTTPClosure>* queue)
+static void HTTPWorkQueueRun(WorkQueue<HTTPClosure>* queue, int worker_num)
 {
-    RenameThread("bitcoin-httpworker");
+    thread_util::Rename(strprintf("httpworker.%i", worker_num));
     queue->Run();
 }
 
@@ -433,7 +434,7 @@ bool StartHTTPServer()
     threadHTTP = std::thread(std::move(task), eventBase, eventHTTP);
 
     for (int i = 0; i < rpcThreads; i++) {
-        g_thread_http_workers.emplace_back(HTTPWorkQueueRun, workQueue);
+        g_thread_http_workers.emplace_back(HTTPWorkQueueRun, workQueue, i);
     }
     return true;
 }
diff --git a/src/init.cpp b/src/init.cpp
index 66b0b65eb4bc6..58253da7d6819 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -36,6 +36,7 @@
 #include <script/sigcache.h>
 #include <scheduler.h>
 #include <shutdown.h>
+#include <threadutil.h>
 #include <timedata.h>
 #include <txdb.h>
 #include <txmempool.h>
@@ -195,7 +196,7 @@ void Shutdown()
     /// 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.
-    RenameThread("bitcoin-shutoff");
+    thread_util::Rename("shutoff");
     mempool.AddTransactionsUpdated(1);
 
     StopHTTPRPC();
@@ -631,7 +632,7 @@ static void CleanupBlockRevFiles()
 static void ThreadImport(std::vector<fs::path> vImportFiles)
 {
     const CChainParams& chainparams = Params();
-    RenameThread("bitcoin-loadblk");
+    thread_util::Rename("loadblk");
     ScheduleBatchPriority();
 
     {
@@ -1264,7 +1265,7 @@ bool AppInitMain()
     LogPrintf("Using %u threads for script verification\n", nScriptCheckThreads);
     if (nScriptCheckThreads) {
         for (int i=0; i<nScriptCheckThreads-1; i++)
-            threadGroup.create_thread(&ThreadScriptCheck);
+            threadGroup.create_thread([i]() { return ThreadScriptCheck(i); });
     }
 
     // Start the lightweight task scheduler thread
diff --git a/src/qt/bitcoin.cpp b/src/qt/bitcoin.cpp
index 3454d3421ea57..e00057de3beeb 100644
--- a/src/qt/bitcoin.cpp
+++ b/src/qt/bitcoin.cpp
@@ -28,6 +28,7 @@
 
 #include <interfaces/handler.h>
 #include <interfaces/node.h>
+#include <threadutil.h>
 #include <rpc/server.h>
 #include <ui_interface.h>
 #include <uint256.h>
@@ -259,6 +260,7 @@ void BitcoinCore::initialize()
     try
     {
         qDebug() << __func__ << ": Running initialization in thread";
+        thread_util::Rename("qt-init");
         bool rv = m_node.appInitMain();
         Q_EMIT initializeResult(rv);
     } catch (const std::exception& e) {
@@ -556,6 +558,7 @@ static void SetupUIArgs()
 int main(int argc, char *argv[])
 {
     SetupEnvironment();
+    thread_util::Rename("main");
 
     std::unique_ptr<interfaces::Node> node = interfaces::MakeNode();
 
diff --git a/src/test/test_bitcoin.cpp b/src/test/test_bitcoin.cpp
index e9814edc23ede..46eb29f83e543 100644
--- a/src/test/test_bitcoin.cpp
+++ b/src/test/test_bitcoin.cpp
@@ -96,7 +96,7 @@ TestingSetup::TestingSetup(const std::string& chainName) : BasicTestingSetup(cha
         }
         nScriptCheckThreads = 3;
         for (int i=0; i < nScriptCheckThreads-1; i++)
-            threadGroup.create_thread(&ThreadScriptCheck);
+            threadGroup.create_thread([i]() { return ThreadScriptCheck(i); });
         g_connman = std::unique_ptr<CConnman>(new CConnman(0x1337, 0x1337)); // Deterministic randomness for tests.
         connman = g_connman.get();
         peerLogic.reset(new PeerLogicValidation(connman, scheduler));
diff --git a/src/threadutil.cpp b/src/threadutil.cpp
new file mode 100644
index 0000000000000..c558c506eeed8
--- /dev/null
+++ b/src/threadutil.cpp
@@ -0,0 +1,76 @@
+// 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.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#include <atomic>
+#include <thread>
+
+#include <threadutil.h>
+
+#ifdef HAVE_SYS_PRCTL_H
+#include <sys/prctl.h> // For prctl, PR_SET_NAME, PR_GET_NAME
+#endif
+
+/**
+ * Set the thread's name at the process level. Does not affect the
+ * internal name.
+ */
+static void SetThreadName(const char* name)
+{
+#if defined(PR_SET_NAME)
+    // Only the first 15 characters are used (16 - NUL terminator)
+    ::prctl(PR_SET_NAME, name, 0, 0, 0);
+#elif (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
+    pthread_set_name_np(pthread_self(), name);
+#elif defined(MAC_OSX)
+    pthread_setname_np(name);
+#else
+    // Prevent warnings for unused parameters...
+    (void)name;
+#endif
+}
+
+/*
+ * If we have thread_local, just keep thread ID and name in a thread_local
+ * global.
+ */
+#if defined(HAVE_THREAD_LOCAL)
+
+static thread_local std::string g_thread_name;
+
+std::string thread_util::GetInternalName() {
+    return g_thread_name;
+}
+
+/**
+ * Set the in-memory internal name for this thread. Does not affect the process
+ * name.
+ */
+static void SetInternalName(const std::string& name)
+{
+    g_thread_name = name;
+}
+
+/**
+ * Without thread_local available, don't handle internal name at all.
+ */
+#else
+
+std::string thread_util::GetInternalName()
+{
+    return "";
+}
+
+static void SetInternalName(const std::string& name) { }
+
+#endif
+
+void thread_util::Rename(const std::string& name)
+{
+    SetThreadName(("bitcoin-" + name).c_str());
+    SetInternalName(name);
+}
diff --git a/src/threadutil.h b/src/threadutil.h
new file mode 100644
index 0000000000000..efff1db1941ed
--- /dev/null
+++ b/src/threadutil.h
@@ -0,0 +1,26 @@
+// 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.
+
+#ifndef BITCOIN_THREADUTIL_H
+#define BITCOIN_THREADUTIL_H
+
+#include <string>
+
+namespace thread_util
+{
+    /**
+     * Rename a thread both in terms of an internal (in-memory) name as well
+     * as its system thread name.
+     */
+    void Rename(const std::string&);
+
+    /**
+     * Get the thread's internal (in-memory) name; used e.g. for identification in
+     * logging.
+     */
+    std::string GetInternalName();
+
+} // namespace thread_util
+
+#endif // BITCOIN_THREADUTIL_H
diff --git a/src/util.cpp b/src/util.cpp
index ab262b40632c2..7f35eedcc8364 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -63,10 +63,6 @@
 #include <shlobj.h>
 #endif
 
-#ifdef HAVE_SYS_PRCTL_H
-#include <sys/prctl.h>
-#endif
-
 #ifdef HAVE_MALLOPT_ARENA_MAX
 #include <malloc.h>
 #endif
@@ -1109,22 +1105,6 @@ void runCommand(const std::string& strCommand)
         LogPrintf("runCommand error: system(%s) returned %d\n", strCommand, nErr);
 }
 
-void RenameThread(const char* name)
-{
-#if defined(PR_SET_NAME)
-    // Only the first 15 characters are used (16 - NUL terminator)
-    ::prctl(PR_SET_NAME, name, 0, 0, 0);
-#elif (defined(__FreeBSD__) || defined(__OpenBSD__) || defined(__DragonFly__))
-    pthread_set_name_np(pthread_self(), name);
-
-#elif defined(MAC_OSX)
-    pthread_setname_np(name);
-#else
-    // Prevent warnings for unused parameters...
-    (void)name;
-#endif
-}
-
 void SetupEnvironment()
 {
 #ifdef HAVE_MALLOPT_ARENA_MAX
diff --git a/src/util.h b/src/util.h
index 8094d72d6b92b..2ef7ad59c8658 100644
--- a/src/util.h
+++ b/src/util.h
@@ -18,6 +18,7 @@
 #include <fs.h>
 #include <logging.h>
 #include <sync.h>
+#include <threadutil.h>
 #include <tinyformat.h>
 #include <utiltime.h>
 
@@ -314,15 +315,12 @@ std::string HelpMessageOpt(const std::string& option, const std::string& message
  */
 int GetNumCores();
 
-void RenameThread(const char* name);
-
 /**
  * .. and a wrapper that just calls func once
  */
 template <typename Callable> void TraceThread(const char* name,  Callable func)
 {
-    std::string s = strprintf("bitcoin-%s", name);
-    RenameThread(s.c_str());
+    thread_util::Rename(name);
     try
     {
         LogPrintf("%s thread start\n", name);
diff --git a/src/validation.cpp b/src/validation.cpp
index 9921063a52216..226455a5e923e 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -43,6 +43,7 @@
 
 #include <future>
 #include <sstream>
+#include <string>
 
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/join.hpp>
@@ -1702,8 +1703,8 @@ static bool WriteUndoDataForBlock(const CBlockUndo& blockundo, CValidationState&
 
 static CCheckQueue<CScriptCheck> scriptcheckqueue(128);
 
-void ThreadScriptCheck() {
-    RenameThread("bitcoin-scriptch");
+void ThreadScriptCheck(int worker_num) {
+    thread_util::Rename(strprintf("scriptch.%i", worker_num));
     scriptcheckqueue.Thread();
 }
 
diff --git a/src/validation.h b/src/validation.h
index 07fe99c079a1c..16713fab6ca16 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -221,7 +221,7 @@ static const unsigned int DEFAULT_CHECKLEVEL = 3;
 // Setting the target to > than 550MB will make it likely we can respect the target.
 static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 550 * 1024 * 1024;
 
-/** 
+/**
  * Process an incoming block. This only returns after the best known valid
  * block is made active. Note that it does not, however, guarantee that the
  * specific block passed to it has been checked for validity!
@@ -232,7 +232,7 @@ static const uint64_t MIN_DISK_SPACE_FOR_BLOCK_FILES = 550 * 1024 * 1024;
  *
  * Note that we guarantee that either the proof-of-work is valid on pblock, or
  * (and possibly also) BlockChecked will have been called.
- * 
+ *
  * May not be called in a
  * validationinterface callback.
  *
@@ -275,7 +275,7 @@ bool LoadChainTip(const CChainParams& chainparams);
 /** Unload database information */
 void UnloadBlockIndex();
 /** Run an instance of the script checking thread */
-void ThreadScriptCheck();
+void ThreadScriptCheck(int worker_num);
 /** Check whether we are doing an initial block download (synchronizing from disk or network) */
 bool IsInitialBlockDownload();
 /** Retrieve a transaction (from memory pool, or from disk, if possible) */
@@ -365,7 +365,7 @@ bool CheckSequenceLocks(const CTransaction &tx, int flags, LockPoints* lp = null
 
 /**
  * Closure representing one script verification
- * Note that this stores references to the spending transaction 
+ * Note that this stores references to the spending transaction
  */
 class CScriptCheck
 {

From 002a570b5da2a1c15fb92e6362a96163eed13dea Mon Sep 17 00:00:00 2001
From: James O'Beirne <james.obeirne@gmail.com>
Date: Sat, 5 May 2018 14:11:46 -0400
Subject: [PATCH 3/5] tests: add threadutil tests

---
 src/Makefile.test.include     |  1 +
 src/test/threadutil_tests.cpp | 73 +++++++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+)
 create mode 100644 src/test/threadutil_tests.cpp

diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index 0c1516f4d5537..a2bcef02aed77 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -80,6 +80,7 @@ BITCOIN_TESTS =\
   test/sigopcount_tests.cpp \
   test/skiplist_tests.cpp \
   test/streams_tests.cpp \
+  test/threadutil_tests.cpp \
   test/timedata_tests.cpp \
   test/torcontrol_tests.cpp \
   test/transaction_tests.cpp \
diff --git a/src/test/threadutil_tests.cpp b/src/test/threadutil_tests.cpp
new file mode 100644
index 0000000000000..3fd1d333dc82f
--- /dev/null
+++ b/src/test/threadutil_tests.cpp
@@ -0,0 +1,73 @@
+// 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 <threadutil.h>
+#include <test/test_bitcoin.h>
+
+#include <thread>
+#include <vector>
+#include <set>
+#include <mutex>
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(threadutil_tests, BasicTestingSetup)
+
+std::string TEST_THREAD_NAME_BASE = "test_thread.";
+
+/**
+ * Run a bunch of threads to all call thread_util::rename.
+ *
+ * @return the set of name each thread has after attempted renaming.
+ */
+std::set<std::string> RenameEnMasse(int num_threads)
+{
+    std::vector<std::thread> threads;
+    std::set<std::string> names;
+    std::mutex lock;
+
+    auto RenameThisThread = [&](int i) {
+        thread_util::Rename(TEST_THREAD_NAME_BASE + std::to_string(i));
+        std::lock_guard<std::mutex> guard(lock);
+        names.insert(thread_util::GetInternalName());
+    };
+
+    for (int i = 0; i < num_threads; ++i) {
+        threads.push_back(std::thread(RenameThisThread, i));
+    }
+
+    for (std::thread& thread : threads) thread.join();
+
+    return names;
+}
+
+/**
+ * Rename a bunch of threads with the same basename (expect_multiple=true), ensuring suffixes are
+ * applied properly.
+ */
+BOOST_AUTO_TEST_CASE(threadutil_test_rename_threaded)
+{
+    BOOST_CHECK_EQUAL(thread_util::GetInternalName(), "");
+
+#if !defined(HAVE_THREAD_LOCAL)
+    // This test doesn't apply to platforms where we don't have thread_local.
+    return;
+#endif
+
+    std::set<std::string> names = RenameEnMasse(100);
+
+    BOOST_CHECK_EQUAL(names.size(), 100);
+
+    // Names "test_thread.[n]" should exist for n = [0, 99]
+    for (int i = 0; i < 100; ++i) {
+        BOOST_CHECK(names.find(TEST_THREAD_NAME_BASE + std::to_string(i)) != names.end());
+    }
+
+}
+
+BOOST_AUTO_TEST_SUITE_END()

From 577ffd40a07b156c1917004a817f07472106066b Mon Sep 17 00:00:00 2001
From: James O'Beirne <james@chaincode.com>
Date: Sat, 5 May 2018 14:14:43 -0400
Subject: [PATCH 4/5] threads: prefix log messages with thread names

Introduce a new flag (`-logthreadnames`) which allows toggling
of this behavior.
---
 doc/release-notes-pr13168.md |  6 ++++++
 src/init.cpp                 |  2 ++
 src/logging.cpp              | 32 ++++++++++++++++++++++----------
 src/logging.h                |  5 ++++-
 4 files changed, 34 insertions(+), 11 deletions(-)
 create mode 100644 doc/release-notes-pr13168.md

diff --git a/doc/release-notes-pr13168.md b/doc/release-notes-pr13168.md
new file mode 100644
index 0000000000000..fd5d5f1d3635a
--- /dev/null
+++ b/doc/release-notes-pr13168.md
@@ -0,0 +1,6 @@
+Thread names in logs
+--------------------
+
+On platforms supporting `thread_local`, log lines are now prefixed by default
+with the name of the thread that caused the log. To disable this behavior,
+specify `-logthreadnames=0`.
diff --git a/src/init.cpp b/src/init.cpp
index 58253da7d6819..d4449644a301e 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -470,6 +470,7 @@ void SetupServerArgs()
     gArgs.AddArg("-help-debug", "Show all debugging options (usage: --help -help-debug)", false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logips", strprintf("Include IP addresses in debug output (default: %u)", DEFAULT_LOGIPS), false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logtimestamps", strprintf("Prepend debug output with timestamp (default: %u)", DEFAULT_LOGTIMESTAMPS), false, 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), false, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS), true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-mocktime=<n>", "Replace actual time with <n> seconds since epoch (default: 0)", true, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-maxsigcachesize=<n>", strprintf("Limit sum of signature cache and script execution cache sizes to <n> MiB (default: %u)", DEFAULT_MAX_SIG_CACHE_SIZE), true, OptionsCategory::DEBUG_TEST);
@@ -836,6 +837,7 @@ void InitLogging()
     g_logger->m_print_to_console = gArgs.GetBoolArg("-printtoconsole", !gArgs.GetBoolArg("-daemon", false));
     g_logger->m_log_timestamps = gArgs.GetBoolArg("-logtimestamps", DEFAULT_LOGTIMESTAMPS);
     g_logger->m_log_time_micros = gArgs.GetBoolArg("-logtimemicros", DEFAULT_LOGTIMEMICROS);
+    g_logger->m_log_threadnames = gArgs.GetBoolArg("-logthreadnames", DEFAULT_LOGTHREADNAMES);
 
     fLogIPs = gArgs.GetBoolArg("-logips", DEFAULT_LOGIPS);
 
diff --git a/src/logging.cpp b/src/logging.cpp
index e8e22cbf97e85..75e600d268063 100644
--- a/src/logging.cpp
+++ b/src/logging.cpp
@@ -5,6 +5,11 @@
 
 #include <logging.h>
 #include <utiltime.h>
+#include <utilstrencodings.h>
+#include <threadutil.h>
+
+#include <list>
+#include <mutex>
 
 const char * const DEFAULT_DEBUGLOGFILE = "debug.log";
 
@@ -168,7 +173,7 @@ std::vector<CLogCategoryActive> ListActiveLogCategories()
     return ret;
 }
 
-std::string BCLog::Logger::LogTimestampStr(const std::string &str)
+std::string BCLog::Logger::LogTimestampStr(std::string str)
 {
     std::string strStamped;
 
@@ -178,6 +183,7 @@ std::string BCLog::Logger::LogTimestampStr(const std::string &str)
     if (m_started_new_line) {
         int64_t nTimeMicros = GetTimeMicros();
         strStamped = FormatISO8601DateTime(nTimeMicros/1000000);
+
         if (m_log_time_micros) {
             strStamped.pop_back();
             strStamped += strprintf(".%06dZ", nTimeMicros%1000000);
@@ -190,21 +196,27 @@ std::string BCLog::Logger::LogTimestampStr(const std::string &str)
     } else
         strStamped = str;
 
-    if (!str.empty() && str[str.size()-1] == '\n')
-        m_started_new_line = true;
-    else
-        m_started_new_line = false;
-
     return strStamped;
 }
 
+std::string BCLog::Logger::LogThreadnameStr(const std::string& str)
+{
+    if (!m_log_threadnames || !m_started_new_line) {
+        return str;
+    }
+    std::string thread_name = thread_util::GetInternalName();
+    return "[" + std::move(thread_name) + "] " + str;
+}
+
 void BCLog::Logger::LogPrintStr(const std::string &str)
 {
-    std::string strTimestamped = LogTimestampStr(str);
+    std::string strPrefixed = LogTimestampStr(LogThreadnameStr(str));
+
+    m_started_new_line = (!str.empty() && str[str.size()-1] == '\n');
 
     if (m_print_to_console) {
         // print to console
-        fwrite(strTimestamped.data(), 1, strTimestamped.size(), stdout);
+        fwrite(strPrefixed.data(), 1, strPrefixed.size(), stdout);
         fflush(stdout);
     }
     if (m_print_to_file) {
@@ -212,7 +224,7 @@ void BCLog::Logger::LogPrintStr(const std::string &str)
 
         // buffer if we haven't opened the log yet
         if (m_fileout == nullptr) {
-            m_msgs_before_open.push_back(strTimestamped);
+            m_msgs_before_open.push_back(strPrefixed);
         }
         else
         {
@@ -226,7 +238,7 @@ void BCLog::Logger::LogPrintStr(const std::string &str)
                 setbuf(m_fileout, nullptr); // unbuffered
             }
 
-            FileWriteStr(strTimestamped, m_fileout);
+            FileWriteStr(strPrefixed, m_fileout);
         }
     }
 }
diff --git a/src/logging.h b/src/logging.h
index 6400b131c2d6b..8794a531ccd4b 100644
--- a/src/logging.h
+++ b/src/logging.h
@@ -19,6 +19,7 @@
 static const bool DEFAULT_LOGTIMEMICROS = false;
 static const bool DEFAULT_LOGIPS        = false;
 static const bool DEFAULT_LOGTIMESTAMPS = true;
+static const bool DEFAULT_LOGTHREADNAMES = true;
 extern const char * const DEFAULT_DEBUGLOGFILE;
 
 extern bool fLogIPs;
@@ -73,7 +74,8 @@ namespace BCLog {
         /** Log categories bitfield. */
         std::atomic<uint32_t> m_categories{0};
 
-        std::string LogTimestampStr(const std::string& str);
+        std::string LogTimestampStr(std::string str);
+        std::string LogThreadnameStr(const std::string& str);
 
     public:
         bool m_print_to_console = false;
@@ -81,6 +83,7 @@ namespace BCLog {
 
         bool m_log_timestamps = DEFAULT_LOGTIMESTAMPS;
         bool m_log_time_micros = DEFAULT_LOGTIMEMICROS;
+        bool m_log_threadnames = DEFAULT_LOGTHREADNAMES;
 
         fs::path m_file_path;
         std::atomic<bool> m_reopen_file{false};

From 91aef702c90d53c8f8dd53dfacb5d5f3d0cb2b91 Mon Sep 17 00:00:00 2001
From: James O'Beirne <james.obeirne@gmail.com>
Date: Sat, 5 May 2018 14:15:30 -0400
Subject: [PATCH 5/5] threads: add thread names to deadlock debugging message

Also refactor CLockLocation to use an initialization list.
---
 src/sync.cpp | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/src/sync.cpp b/src/sync.cpp
index 28a4e37e68d05..5491b28a4174f 100644
--- a/src/sync.cpp
+++ b/src/sync.cpp
@@ -3,8 +3,10 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <sync.h>
+#include <tinyformat.h>
 
 #include <logging.h>
+#include <threadutil.h>
 #include <utilstrencodings.h>
 
 #include <stdio.h>
@@ -37,23 +39,23 @@ void PrintLockContention(const char* pszName, const char* pszFile, int nLine)
 //
 
 struct CLockLocation {
-    CLockLocation(const char* pszName, const char* pszFile, int nLine, bool fTryIn)
-    {
-        mutexName = pszName;
-        sourceFile = pszFile;
-        sourceLine = nLine;
-        fTry = fTryIn;
-    }
+    CLockLocation(
+        const char* pszName, const char* pszFile, int nLine, bool fTryIn, std::string thread_name_) :
+            mutexName(pszName), sourceFile(pszFile), sourceLine(nLine), fTry(fTryIn),
+            thread_name(std::move(thread_name_)) { }
 
     std::string ToString() const
     {
-        return mutexName + "  " + sourceFile + ":" + itostr(sourceLine) + (fTry ? " (TRY)" : "");
+        return tfm::format(
+            "%s %s:%s%s (in thread %s)",
+            mutexName, sourceFile, itostr(sourceLine), (fTry ? " (TRY)" : ""), thread_name);
     }
 
 private:
     bool fTry;
     std::string mutexName;
     std::string sourceFile;
+    std::string thread_name;
     int sourceLine;
 };
 
@@ -132,7 +134,7 @@ static void pop_lock()
 
 void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry)
 {
-    push_lock(cs, CLockLocation(pszName, pszFile, nLine, fTry));
+    push_lock(cs, CLockLocation(pszName, pszFile, nLine, fTry, thread_util::GetInternalName()));
 }
 
 void LeaveCritical()