Make killing of threads safer

Docs/manual.texi

@@ -46712,6 +46712,9 @@ not yet 100% confident in this code.
 @appendixsubsec Changes in release 3.23.42
 @itemize @bullet
 @item
+Fixed rare hang when doing @code{mysqladmin shutdown} when there was
+a lot of activity in other threads.
+@item
 Fixed problem with @code{INSERT DELAYED} where delay thread could be
 hanging on @code{upgrading locks} without any apparent reasons.
 @item

include/my_pthread.h

@@ -575,12 +575,14 @@ extern int pthread_dummy(int);
 struct st_my_thread_var
 {
   int thr_errno;
-  pthread_cond_t suspend, *current_cond;
+  pthread_cond_t suspend;
-  pthread_mutex_t mutex,  *current_mutex;
+  pthread_mutex_t mutex;
+  pthread_mutex_t * volatile current_mutex;
+  pthread_cond_t * volatile current_cond;
   pthread_t pthread_self;
   long id;
   int cmp_length;
-  volatile int abort;
+  int volatile abort;
 #ifndef DBUG_OFF
   gptr dbug;
   char name[THREAD_NAME_SIZE+1];

mysys/thr_lock.c

@@ -374,16 +374,16 @@ static my_bool wait_for_lock(struct st_lock_list *wait, THR_LOCK_DATA *data,
   }
 
   /* Set up control struct to allow others to abort locks */
-  pthread_mutex_lock(&thread_var->mutex);
   thread_var->current_mutex= &data->lock->mutex;
   thread_var->current_cond=  cond;
-  pthread_mutex_unlock(&thread_var->mutex);
 
   data->cond=cond;
-  do
+  while (!thread_var->abort || in_wait_list)
   {
     pthread_cond_wait(cond,&data->lock->mutex);
-  } while (data->cond == cond && (!thread_var->abort || in_wait_list));
+    if (data->cond != cond)
+      break;
+  }
 
   if (data->cond || data->type == TL_UNLOCK)
   {

sql/item_func.cc

@@ -1483,11 +1483,9 @@ longlong Item_func_get_lock::val_int()
 
   /* structure is now initialized.  Try to get the lock */
   /* Set up control struct to allow others to abort locks */
-  pthread_mutex_lock(&thd->mysys_var->mutex);
   thd->proc_info="User lock";
   thd->mysys_var->current_mutex= &LOCK_user_locks;
   thd->mysys_var->current_cond=  &ull->cond;
-  pthread_mutex_unlock(&thd->mysys_var->mutex);
 
 #ifdef HAVE_TIMESPEC_TS_SEC
   abstime.ts_sec=time((time_t*) 0)+(time_t) timeout;
@@ -1497,15 +1495,11 @@ longlong Item_func_get_lock::val_int()
   abstime.tv_nsec=0;
 #endif
 
-  while ((error=pthread_cond_timedwait(&ull->cond,&LOCK_user_locks,&abstime))
+  while (!thd->killed &&
-	 != ETIME && error != ETIMEDOUT && ull->locked)
+	 (error=pthread_cond_timedwait(&ull->cond,&LOCK_user_locks,&abstime))
-  {
+	 != ETIME && error != ETIMEDOUT && ull->locked) ;
-    if (thd->killed || abort_loop)
+  if (thd->killed)
-    {
+    error=EINTR;				// Return NULL
-      error=EINTR;				// Return NULL
-      break;
-    }
-  }
   if (ull->locked)
   {
     if (!--ull->count)

sql/lock.cc

@@ -65,11 +65,9 @@ MYSQL_LOCK *mysql_lock_tables(THD *thd,TABLE **tables,uint count)
       }	
 
       pthread_mutex_lock(&LOCK_open);
-      pthread_mutex_lock(&thd->mysys_var->mutex);
       thd->mysys_var->current_mutex= &LOCK_open;
       thd->mysys_var->current_cond= &COND_refresh;
       thd->proc_info="Waiting for table";
-      pthread_mutex_unlock(&thd->mysys_var->mutex);
 
       while (global_read_lock && ! thd->killed &&
 	     thd->version == refresh_version)

sql/sql_base.cc

@@ -358,11 +358,9 @@ bool close_cached_tables(THD *thd, bool if_wait_for_refresh,
     */
     if (!tables)
       kill_delayed_threads();
-    pthread_mutex_lock(&thd->mysys_var->mutex);
     thd->mysys_var->current_mutex= &LOCK_open;
     thd->mysys_var->current_cond= &COND_refresh;
     thd->proc_info="Flushing tables";
-    pthread_mutex_unlock(&thd->mysys_var->mutex);
 
     close_old_data_files(thd,thd->open_tables,1,1);
     bool found=1;
@@ -667,13 +665,12 @@ void wait_for_refresh(THD *thd)
 {
   /* Wait until the current table is up to date */
   const char *proc_info;
-  pthread_mutex_lock(&thd->mysys_var->mutex);
   thd->mysys_var->current_mutex= &LOCK_open;
   thd->mysys_var->current_cond= &COND_refresh;
   proc_info=thd->proc_info;
   thd->proc_info="Waiting for table";
-  pthread_mutex_unlock(&thd->mysys_var->mutex);
+  if (!thd->killed)
-  (void) pthread_cond_wait(&COND_refresh,&LOCK_open);
+    (void) pthread_cond_wait(&COND_refresh,&LOCK_open);
 
   pthread_mutex_unlock(&LOCK_open);	// Must be unlocked first
   pthread_mutex_lock(&thd->mysys_var->mutex);
@@ -2182,7 +2179,7 @@ bool remove_table_from_cache(THD *thd, const char *db, const char *table_name,
       {
 	in_use->killed=1;
 	pthread_mutex_lock(&in_use->mysys_var->mutex);
-	if (in_use->mysys_var->current_mutex)
+	if (in_use->mysys_var->current_cond)
 	{
 	  pthread_mutex_lock(in_use->mysys_var->current_mutex);
 	  pthread_cond_broadcast(in_use->mysys_var->current_cond);

sql/sql_class.h

@@ -326,11 +326,9 @@ public:
 			  const char* msg)
   {
     const char* old_msg = proc_info;
-    pthread_mutex_lock(&mysys_var->mutex);
     mysys_var->current_mutex = mutex;
     mysys_var->current_cond = cond;
     proc_info = msg;
-    pthread_mutex_unlock(&mysys_var->mutex);
     return old_msg;
   }
   inline void exit_cond(const char* old_msg)

sql/sql_insert.cc

@@ -482,7 +482,7 @@ public:
   COPY_INFO info;
   I_List<delayed_row> rows;
   uint group_count;
-  TABLE_LIST *table_list;			// Argument
+  TABLE_LIST table_list;			// Argument
 
   delayed_insert()
     :locks_in_memory(0),
@@ -611,7 +611,9 @@ static TABLE *delayed_get_table(THD *thd,TABLE_LIST *table_list)
 	pthread_mutex_unlock(&LOCK_delayed_create);
 	DBUG_RETURN(0);
       }
-      tmp->table_list=table_list;			// Needed to open table
+      tmp->table_list= *table_list;			// Needed to open table
+      tmp->table_list.db= tmp->thd.db;
+      tmp->table_list.name= tmp->table_list.real_name=tmp->thd.query;
       tmp->lock();
       pthread_mutex_lock(&tmp->mutex);
       if ((error=pthread_create(&tmp->thd.real_id,&connection_attrib,
@@ -846,11 +848,9 @@ void kill_delayed_threads(void)
       pthread_mutex_lock(&tmp->thd.mysys_var->mutex);
       if (tmp->thd.mysys_var->current_cond)
       {
-	if (&tmp->mutex != tmp->thd.mysys_var->current_mutex)
+	pthread_mutex_lock(tmp->thd.mysys_var->current_mutex);
-	  pthread_mutex_lock(tmp->thd.mysys_var->current_mutex);
 	pthread_cond_broadcast(tmp->thd.mysys_var->current_cond);
-	if (&tmp->mutex != tmp->thd.mysys_var->current_mutex)
+	pthread_mutex_unlock(tmp->thd.mysys_var->current_mutex);
-	  pthread_mutex_unlock(tmp->thd.mysys_var->current_mutex);
       }
       pthread_mutex_unlock(&tmp->thd.mysys_var->mutex);
     }
@@ -875,6 +875,7 @@ static pthread_handler_decl(handle_delayed_insert,arg)
   thd->thread_id=thread_id++;
   thd->end_time();
   threads.append(thd);
+  thd->killed=abort_loop;
   pthread_mutex_unlock(&LOCK_thread_count);
 
   pthread_mutex_lock(&di->mutex);
@@ -905,7 +906,7 @@ static pthread_handler_decl(handle_delayed_insert,arg)
 
   /* open table */
 
-  if (!(di->table=open_ltable(thd,di->table_list,TL_WRITE_DELAYED)))
+  if (!(di->table=open_ltable(thd,&di->table_list,TL_WRITE_DELAYED)))
   {
     thd->fatal_error=1;				// Abort waiting inserts
     goto end;
@@ -913,7 +914,7 @@ static pthread_handler_decl(handle_delayed_insert,arg)
   if (di->table->file->has_transactions())
   {
     thd->fatal_error=1;
-    my_error(ER_ILLEGAL_HA, MYF(0), di->table_list->real_name);
+    my_error(ER_ILLEGAL_HA, MYF(0), di->table_list.real_name);
     goto end;
   }
   di->table->copy_blobs=1;
@@ -965,10 +966,8 @@ static pthread_handler_decl(handle_delayed_insert,arg)
 #endif
 
       /* Information for pthread_kill */
-      pthread_mutex_lock(&di->thd.mysys_var->mutex);
       di->thd.mysys_var->current_mutex= &di->mutex;
       di->thd.mysys_var->current_cond= &di->cond;
-      pthread_mutex_unlock(&di->thd.mysys_var->mutex);
       di->thd.proc_info=0;
 
       DBUG_PRINT("info",("Waiting for someone to insert rows"));
@@ -996,10 +995,13 @@ static pthread_handler_decl(handle_delayed_insert,arg)
 	  break;
 	}
       }
+      /* We can't lock di->mutex and mysys_var->mutex at the same time */
+      pthread_mutex_unlock(&di->mutex);
       pthread_mutex_lock(&di->thd.mysys_var->mutex);
       di->thd.mysys_var->current_mutex= 0;
       di->thd.mysys_var->current_cond= 0;
       pthread_mutex_unlock(&di->thd.mysys_var->mutex);
+      pthread_mutex_lock(&di->mutex);
     }
 
     if (di->tables_in_use && ! thd->lock)

sql/sql_repl.cc

@@ -414,12 +414,10 @@ void mysql_binlog_send(THD* thd, char* log_ident, ulong pos, ushort flags)
 	log.error=0;
 
 	// tell the kill thread how to wake us up
-	pthread_mutex_lock(&thd->mysys_var->mutex);
 	thd->mysys_var->current_mutex = log_lock;
 	thd->mysys_var->current_cond = &COND_binlog_update;
 	const char* proc_info = thd->proc_info;
 	thd->proc_info = "Slave connection: waiting for binlog update";
-	pthread_mutex_unlock(&thd->mysys_var->mutex);
 
 	bool read_packet = 0, fatal_error = 0;
 
@@ -444,7 +442,8 @@ void mysql_binlog_send(THD* thd, char* log_ident, ulong pos, ushort flags)
 	  break;
 	case LOG_READ_EOF:
 	  DBUG_PRINT("wait",("waiting for data on binary log"));
-	  pthread_cond_wait(&COND_binlog_update, log_lock);
+	  if (!thd->killed)
+	    pthread_cond_wait(&COND_binlog_update, log_lock);
 	  break;
 
 	default:
@@ -694,9 +693,9 @@ void kill_zombie_dump_threads(uint32 slave_server_id)
 	  
 	  thr_alarm_kill(tmp->real_id);
 	  tmp->killed = 1;
-	  pthread_mutex_lock(&tmp->mysys_var->mutex);
           tmp->mysys_var->abort = 1;
-	  if(tmp->mysys_var->current_mutex)
+	  pthread_mutex_lock(&tmp->mysys_var->mutex);
+	  if(tmp->mysys_var->current_cond)
 	    {
 	      pthread_mutex_lock(tmp->mysys_var->current_mutex);
 	      pthread_cond_broadcast(tmp->mysys_var->current_cond);

sql/sql_table.cc

@@ -53,11 +53,9 @@ int mysql_rm_table(THD *thd,TABLE_LIST *tables, my_bool if_exists)
 
   /* mark for close and remove all cached entries */
 
-  pthread_mutex_lock(&thd->mysys_var->mutex);
   thd->mysys_var->current_mutex= &LOCK_open;
   thd->mysys_var->current_cond= &COND_refresh;
   VOID(pthread_mutex_lock(&LOCK_open));
-  pthread_mutex_unlock(&thd->mysys_var->mutex);
 
   if (global_read_lock)
   {