MDEV-32537 Name threads to improve debugging experience and diagnostics.

Use SetThreadDescription/pthread_setname_np to give threads a name.

Author: vaintroub

include/mysql/psi/psi.h

@@ -1624,6 +1624,12 @@ typedef void (*set_thread_os_id_v1_t)(struct PSI_thread *thread);
 */
 typedef struct PSI_thread* (*get_thread_v1_t)(void);
 
+/**
+ Get name of the thread, according to the thread class.
+ The name is returns without the thread/subsystem prefix.
+*/
+typedef const char* (*get_thread_class_name_v1_t)(void);
+
 /**
  Assign a user name to the instrumented thread.
  @param user the user name
@@ -2538,6 +2544,8 @@ struct PSI_v1
  set_thread_os_id_v1_t set_thread_os_id;
  /** @sa get_thread_v1_t. */
  get_thread_v1_t get_thread;
+ /** @sa get_thread_name_v1_t. */
+ get_thread_class_name_v1_t get_thread_class_name;
  /** @sa set_thread_user_v1_t. */
  set_thread_user_v1_t set_thread_user;
  /** @sa set_thread_account_v1_t. */

include/mysql/psi/psi_abi_v1.h.pp

@@ -449,6 +449,7 @@
  ulonglong id);
 typedef void (*set_thread_os_id_v1_t)(struct PSI_thread *thread);
 typedef struct PSI_thread* (*get_thread_v1_t)(void);
+typedef const char* (*get_thread_class_name_v1_t)(void);
 typedef void (*set_thread_user_v1_t)(const char *user, int user_len);
 typedef void (*set_thread_account_v1_t)(const char *user, int user_len,
  const char *host, int host_len);
@@ -725,6 +726,7 @@
  set_thread_THD_v1_t set_thread_THD;
  set_thread_os_id_v1_t set_thread_os_id;
  get_thread_v1_t get_thread;
+ get_thread_class_name_v1_t get_thread_class_name;
  set_thread_user_v1_t set_thread_user;
  set_thread_account_v1_t set_thread_account;
  set_thread_db_v1_t set_thread_db;

include/pfs_thread_provider.h

@@ -80,6 +80,8 @@ void pfs_set_thread_os_id_v1(PSI_thread *thread);
 PSI_thread*
 pfs_get_thread_v1(void);
 
+const char *pfs_get_thread_class_name_v1(void);
+
 void pfs_set_thread_user_v1(const char *user, int user_len);
 
 void pfs_set_thread_account_v1(const char *user, int user_len,

mysys/CMakeLists.txt

@@ -46,7 +46,7 @@ SET(MYSYS_SOURCES array.c charset-def.c charset.c my_default.c
 my_rdtsc.c psi_noop.c
  my_atomic_writes.c my_cpu.c my_likely.c my_largepage.c
  file_logger.c my_dlerror.c crc32/crc32c.cc
- my_timezone.cc)
+ my_timezone.cc my_thread_name.cc)
 
 IF (WIN32)
  SET (MYSYS_SOURCES ${MYSYS_SOURCES}

mysys/my_thr_init.c

@@ -172,35 +172,6 @@ my_bool my_thread_global_init(void)
  return 0;
 }
 
-#ifdef _WIN32
-#define MAX_THREAD_NAME 256
-#elif defined(__linux__)
-#define MAX_THREAD_NAME 16
-#elif defined(__FreeBSD__) || defined(__OpenBSD__)
-#include <pthread_np.h>
-#endif
-
-void my_thread_set_name(const char *name)
-{
-#ifdef _WIN32
- wchar_t wname[MAX_THREAD_NAME];
- wname[0]= 0;
- MultiByteToWideChar(CP_UTF8, 0, name, -1, wname, MAX_THREAD_NAME);
- SetThreadDescription(GetCurrentThread(), wname);
-#elif defined __linux__
- char shortname[MAX_THREAD_NAME];
- snprintf(shortname, MAX_THREAD_NAME, "%s", name);
- pthread_setname_np(pthread_self(), shortname);
-#elif defined __NetBSD__
- pthread_setname_np(pthread_self(), "%s", (void *) name);
-#elif defined __FreeBSD__ || defined __OpenBSD__
- pthread_set_name_np(pthread_self(), name);
-#elif defined __APPLE__
- pthread_setname_np(name);
-#else
- (void) name;
-#endif
-}
 
 /**
  End the mysys thread system. Called when ending the last thread

mysys/my_thread_name.cc

@@ -0,0 +1,97 @@
+/* Copyright 2024, MariaDB.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
+
+#include <my_global.h>
+#include <my_pthread.h>
+#include <my_sys.h>
+#include "mysql/psi/psi.h"
+#include <stdio.h>
+
+#ifdef _WIN32
+#define MAX_THREAD_NAME 256
+typedef HRESULT (*func_SetThreadDescription)(HANDLE,PCWSTR);
+#elif defined(__linux__)
+#define MAX_THREAD_NAME 16
+#elif defined(__FreeBSD__) || defined(__OpenBSD__)
+#include <pthread_np.h>
+#endif
+
+#if defined(HAVE_PSI_THREAD_INTERFACE) && !defined DBUG_OFF
+/**
+ Check that the name is consistent with PSI.
+ Require that the name matches the last part of PSI's class name
+ (e.g. "thread/sql/main" -> "main").
+
+ We drop the namespace prefix, because these thread names are
+ truncated to 15 characters on Linux, and something like "innodb/" would
+ already take up about half of that.
+*/
+static void dbug_verify_thread_name(const char *name)
+{
+ const char *psi_name= NULL;
+ const char *thread_class_name= PSI_THREAD_CALL(get_thread_class_name)();
+ if (thread_class_name)
+ {
+ /* Remove the path prefix */
+ const char *last_part= strrchr(thread_class_name, '/');
+ if (last_part)
+ psi_name= last_part + 1;
+ else
+ psi_name= thread_class_name;
+ }
+ if (psi_name && strcmp(psi_name, name))
+ {
+ fprintf(stderr, "my_thread_set_name() mismatch: PSI name '%s' != '%s'\n",
+ psi_name, name);
+ abort();
+ }
+}
+#else
+#define dbug_verify_thread_name(name) do {} while (0)
+#endif
+
+/* Set current thread name for debugger/profiler and similar tools. */
+extern "C" void my_thread_set_name(const char *name)
+{
+ dbug_verify_thread_name(name);
+
+#ifdef _WIN32
+ /*
+ SetThreadDescription might not be there on older Windows versions.
+ Load it dynamically.
+ */
+ static func_SetThreadDescription my_SetThreadDescription=
+ (func_SetThreadDescription) GetProcAddress(GetModuleHandle("kernel32"),
+ "SetThreadDescription");
+ if (!my_SetThreadDescription)
+ return;
+ wchar_t wname[MAX_THREAD_NAME];
+ wname[0]= 0;
+ MultiByteToWideChar(CP_UTF8, 0, name, -1, wname, MAX_THREAD_NAME);
+ my_SetThreadDescription(GetCurrentThread(), wname);
+#elif defined __linux__
+ char shortname[MAX_THREAD_NAME];
+ snprintf(shortname, MAX_THREAD_NAME, "%s", name);
+ pthread_setname_np(pthread_self(), shortname);
+#elif defined __NetBSD__
+ pthread_setname_np(pthread_self(), "%s", (void *) name);
+#elif defined __FreeBSD__ || defined __OpenBSD__
+ pthread_set_name_np(pthread_self(), name);
+#elif defined __APPLE__
+ pthread_setname_np(name);
+#else
+ (void) name;
+#endif
+}

mysys/psi_noop.c

@@ -228,6 +228,11 @@ get_thread_noop(void NNN)
  return NULL;
 }
 
+static const char* get_thread_class_name_noop(void)
+{
+ return NULL;
+}
+
 static void set_thread_user_noop(const char *user NNN, int user_len NNN)
 {
  return;
@@ -938,6 +943,7 @@ static PSI PSI_noop=
  set_thread_THD_noop,
  set_thread_os_id_noop,
  get_thread_noop,
+ get_thread_class_name_noop,
  set_thread_user_noop,
  set_thread_user_host_noop,
  set_thread_db_noop,

sql/mysqld.cc

@@ -3219,7 +3219,7 @@ pthread_handler_t signal_hand(void *)
  sigset_t set;
  int sig;
  my_thread_init();// Init new thread
- my_thread_set_name("signal_hand");
+ my_thread_set_name("signal_handler");
  signal_thread_in_use= 1;
 
  if (test_flags & TEST_SIGINT)

sql/rpl_parallel.cc

@@ -1226,7 +1226,7 @@ handle_rpl_parallel_thread(void *arg)
  struct rpl_parallel_thread *rpt= (struct rpl_parallel_thread *)arg;
 
  my_thread_init();
- my_thread_set_name("rpl_parallel");
+ my_thread_set_name("rpl_parallel_thread");
  thd = new THD(next_thread_id());
  thd->thread_stack = (char*)&thd;
  server_threads.insert(thd);

sql/semisync_master_ack_receiver.cc

@@ -33,7 +33,7 @@ pthread_handler_t ack_receive_handler(void *arg)
  Ack_receiver *recv= reinterpret_cast<Ack_receiver *>(arg);
 
  my_thread_init();
- my_thread_set_name("ack_receive");
+ my_thread_set_name("Ack_receiver");
  recv->run();
  my_thread_end();