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Get rid of idle thread counter atomic variable.

Browse source 
Instead, use function that loops over groups and 
calculates  idle threads for  "show status".
This commit is contained in:
Vladislav Vaintroub 2012-01-15 15:41:25 +01:00
commit d212991e89
4 changed files with 53 additions and 23 deletions
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13
sql/mysqld.cc
View file

@ -7008,6 +7008,15 @@ static int show_default_keycache(THD *thd, SHOW_VAR *var, char *buff)
return 0;
}
#ifdef HAVE_POOL_OF_THREADS
int show_threadpool_idle_threads(THD *thd, SHOW_VAR *var, char *buff)
{
var->type= SHOW_INT;
var->value= buff;
*(int *)buff= tp_get_idle_thread_count();
return 0;
}
#endif
/*
Variables shown by SHOW STATUS in alphabetical order
@ -7144,8 +7153,8 @@ SHOW_VAR status_vars[]= {
{"Tc_log_page_size", (char*) &tc_log_page_size, SHOW_LONG},
{"Tc_log_page_waits", (char*) &tc_log_page_waits, SHOW_LONG},
#endif
#ifndef EMBEDDED_LIBRARY
{"Threadpool_idle_threads", (char *) &tp_stats.num_waiting_threads, SHOW_INT},
#ifdef HAVE_POOL_OF_THREADS
{"Threadpool_idle_threads", (char *) &show_threadpool_idle_threads, SHOW_FUNC},
{"Threadpool_threads", (char *) &tp_stats.num_worker_threads, SHOW_INT},
#endif
{"Threads_cached", (char*) &cached_thread_count, SHOW_LONG_NOFLUSH},

7
sql/threadpool.h
View file

@ -22,6 +22,9 @@ extern void tp_wait_end(THD*);
extern void tp_post_kill_notification(THD *thd);
extern void tp_end(void);
/* Used in SHOW for threadpool_idle_thread_count */
extern int tp_get_idle_thread_count();
/*
Threadpool statistics
*/
@ -29,8 +32,6 @@ struct TP_STATISTICS
{
/* Current number of worker thread. */
volatile int32 num_worker_threads;
/* Current number of idle threads. */
volatile int32 num_waiting_threads;
};
extern TP_STATISTICS tp_stats;
@ -45,3 +46,5 @@ extern void tp_set_threadpool_stall_limit(uint val);
/* Activate threadpool scheduler */
extern void tp_scheduler(void);
extern int show_threadpool_idle_threads(THD *thd, SHOW_VAR *var, char *buff);

44
sql/threadpool_unix.cc
View file

@ -384,18 +384,6 @@ static connection_t *queue_get(thread_group_t *thread_group)
}
static void increment_active_threads(thread_group_t *thread_group)
{
my_atomic_add32(&tp_stats.num_waiting_threads,-1);
thread_group->active_thread_count++;
}
static void decrement_active_threads(thread_group_t *thread_group)
{
my_atomic_add32(&tp_stats.num_waiting_threads,1);
thread_group->active_thread_count--;
}
/*
Handle wait timeout :
@ -585,7 +573,7 @@ static connection_t * listener(worker_thread_t *current_thread,
connection_t *retval= NULL;
decrement_active_threads(thread_group);
for(;;)
{
native_event ev[MAX_EVENTS];
@ -594,7 +582,9 @@ static connection_t * listener(worker_thread_t *current_thread,
if (thread_group->shutdown)
break;
thread_group->active_thread_count--;
cnt = io_poll_wait(thread_group->pollfd, ev, MAX_EVENTS, -1);
thread_group->active_thread_count++;
if (cnt <=0)
{
@ -705,7 +695,7 @@ static connection_t * listener(worker_thread_t *current_thread,
}
}
increment_active_threads(thread_group);
DBUG_RETURN(retval);
}
@ -1037,12 +1027,12 @@ connection_t *get_event(worker_thread_t *current_thread,
*/
thread_group->waiting_threads.push_front(current_thread);
decrement_active_threads(thread_group);
thread_group->active_thread_count--;
if(abstime)
err = mysql_cond_timedwait(&current_thread->cond, &thread_group->mutex, abstime);
else
err = mysql_cond_wait(&current_thread->cond, &thread_group->mutex);
increment_active_threads(thread_group);
thread_group->active_thread_count++;
if (!current_thread->woken)
{
@ -1076,7 +1066,8 @@ void wait_begin(thread_group_t *thread_group)
{
DBUG_ENTER("wait_begin");
mysql_mutex_lock(&thread_group->mutex);
decrement_active_threads(thread_group);
thread_group->active_thread_count--;
DBUG_ASSERT(thread_group->active_thread_count >=0);
DBUG_ASSERT(thread_group->connection_count > 0);
@ -1102,7 +1093,7 @@ void wait_end(thread_group_t *thread_group)
{
DBUG_ENTER("wait_end");
mysql_mutex_lock(&thread_group->mutex);
increment_active_threads(thread_group);
thread_group->active_thread_count++;
mysql_mutex_unlock(&thread_group->mutex);
DBUG_VOID_RETURN;
}
@ -1525,3 +1516,20 @@ void tp_set_threadpool_stall_limit(uint limit)
mysql_cond_signal(&(pool_timer.cond));
mysql_mutex_unlock(&(pool_timer.mutex));
}
/**
Calculate number of idle/waiting threads in the pool.
Sum idle threads over all groups.
Don't do any locking, it is not required for stats.
*/
int tp_get_idle_thread_count()
{
int sum=0;
for(uint i= 0; i< array_elements(all_groups) && (all_groups[i].pollfd >= 0); i++)
{
sum+= (all_groups[i].thread_count - all_groups[i].active_thread_count);
}
return sum;
}

10
sql/threadpool_win.cc
View file

@ -753,3 +753,13 @@ void tp_wait_end(THD *thd)
/* Do we need to do anything ? */
}
/**
Number of idle threads in pool.
This info is not available in Windows implementation,
thus function always returns 0.
*/
int tp_get_idle_thread_count()
{
return 0;
}