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MDEV-5289: master server starts slave parallel threads

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Delay spawning parallel replication worker threads until a slave SQL
thread is running, and de-spawn them when the last SQL thread stops.

This is especially useful to avoid needless threads on a master in a
setup where same my.cnf is used on masters and slaves.
This commit is contained in:
Kristian Nielsen
2015-03-11 09:18:16 +01:00
parent a7fd11b31d
commit ed04c40b01
11 changed files with 116 additions and 53 deletions
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63
sql/rpl_parallel.cc
View File

@@ -944,9 +944,9 @@ dealloc_gco(group_commit_orderer *gco)
}
int
static int
rpl_parallel_change_thread_count(rpl_parallel_thread_pool *pool,
uint32 new_count, bool skip_check)
uint32 new_count)
{
uint32 i;
rpl_parallel_thread **new_list= NULL;
@@ -991,24 +991,6 @@ rpl_parallel_change_thread_count(rpl_parallel_thread_pool *pool,
new_free_list= new_list[i];
}
if (!skip_check)
{
mysql_mutex_lock(&LOCK_active_mi);
if (master_info_index->give_error_if_slave_running())
{
mysql_mutex_unlock(&LOCK_active_mi);
goto err;
}
if (pool->changing)
{
mysql_mutex_unlock(&LOCK_active_mi);
my_error(ER_CHANGE_SLAVE_PARALLEL_THREADS_ACTIVE, MYF(0));
goto err;
}
pool->changing= true;
mysql_mutex_unlock(&LOCK_active_mi);
}
/*
Grab each old thread in turn, and signal it to stop.
@@ -1068,13 +1050,6 @@ rpl_parallel_change_thread_count(rpl_parallel_thread_pool *pool,
mysql_mutex_unlock(&pool->threads[i]->LOCK_rpl_thread);
}
if (!skip_check)
{
mysql_mutex_lock(&LOCK_active_mi);
pool->changing= false;
mysql_mutex_unlock(&LOCK_active_mi);
}
mysql_mutex_lock(&pool->LOCK_rpl_thread_pool);
mysql_cond_broadcast(&pool->COND_rpl_thread_pool);
mysql_mutex_unlock(&pool->LOCK_rpl_thread_pool);
@@ -1101,16 +1076,26 @@ err:
}
my_free(new_list);
}
if (!skip_check)
{
mysql_mutex_lock(&LOCK_active_mi);
pool->changing= false;
mysql_mutex_unlock(&LOCK_active_mi);
}
return 1;
}
int
rpl_parallel_activate_pool(rpl_parallel_thread_pool *pool)
{
if (!pool->count)
return rpl_parallel_change_thread_count(pool, opt_slave_parallel_threads);
return 0;
}
int
rpl_parallel_inactivate_pool(rpl_parallel_thread_pool *pool)
{
return rpl_parallel_change_thread_count(pool, 0);
}
void
rpl_parallel_thread::batch_free()
{
@@ -1354,7 +1339,7 @@ rpl_parallel_thread::loc_free_gco(group_commit_orderer *gco)
rpl_parallel_thread_pool::rpl_parallel_thread_pool()
: count(0), threads(0), free_list(0), changing(false), inited(false)
: count(0), threads(0), free_list(0), inited(false)
{
}
@@ -1369,10 +1354,14 @@ rpl_parallel_thread_pool::init(uint32 size)
mysql_mutex_init(key_LOCK_rpl_thread_pool, &LOCK_rpl_thread_pool,
MY_MUTEX_INIT_SLOW);
mysql_cond_init(key_COND_rpl_thread_pool, &COND_rpl_thread_pool, NULL);
changing= false;
inited= true;
return rpl_parallel_change_thread_count(this, size, true);
/*
The pool is initially empty. Threads will be spawned when a slave SQL
thread is started.
*/
return 0;
}
@@ -1381,7 +1370,7 @@ rpl_parallel_thread_pool::destroy()
{
if (!inited)
return;
rpl_parallel_change_thread_count(this, 0, true);
rpl_parallel_change_thread_count(this, 0);
mysql_mutex_destroy(&LOCK_rpl_thread_pool);
mysql_cond_destroy(&COND_rpl_thread_pool);
inited= false;