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

Use SetThreadDescription/pthread_setname_np to give threads a name.

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 @@ typedef void (*set_thread_id_v1_t)(struct PSI_thread *thread,
                                    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 @@ struct PSI_v1
   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

+/* 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();
 

sql/sql_manager.cc

@@ -75,7 +75,7 @@ pthread_handler_t handle_manager(void *arg __attribute__((unused)))
   struct timespec abstime;
   bool reset_flush_time = TRUE;
   my_thread_init();
-  my_thread_set_name("handle_manager");
+  my_thread_set_name("manager");
   DBUG_ENTER("handle_manager");
 
   pthread_detach_this_thread();

sql/threadpool_generic.cc

@@ -1534,7 +1534,7 @@ static void *worker_main(void *param)
   worker_thread_t this_thread;
   pthread_detach_this_thread();
   my_thread_init();
-  my_thread_set_name("connection_worker");
+  my_thread_set_name("worker_thread");
 
   DBUG_ENTER("worker_main");
 

storage/maria/ma_checkpoint.c

@@ -577,7 +577,7 @@ pthread_handler_t ma_checkpoint_background(void *arg)
   PAGECACHE_FILE *UNINIT_VAR(kfile); /**< index file currently being flushed */
 
   my_thread_init();
-  my_thread_set_name("ma_checkpoint_background");
+  my_thread_set_name("checkpoint_background");
   DBUG_PRINT("info",("Maria background checkpoint thread starts"));
   DBUG_ASSERT(interval > 0);
 

storage/perfschema/pfs.cc

@@ -2325,6 +2325,14 @@ pfs_get_thread_v1(void)
   return reinterpret_cast<PSI_thread*> (pfs);
 }
 
+const char *pfs_get_thread_class_name_v1(void)
+{
+  PFS_thread *pfs= my_thread_get_THR_PFS();
+  if (!pfs)
+    return NULL;
+  return pfs->m_class->m_name;
+}
+
 /**
   Implementation of the thread instrumentation interface.
   @sa PSI_v1::set_thread_user.
@@ -7040,6 +7048,7 @@ PSI_v1 PFS_v1=
   pfs_set_thread_THD_v1,
   pfs_set_thread_os_id_v1,
   pfs_get_thread_v1,
+  pfs_get_thread_class_name_v1,
   pfs_set_thread_user_v1,
   pfs_set_thread_account_v1,
   pfs_set_thread_db_v1,