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Bug#40536: SELECT is blocked by INSERT DELAYED waiting on

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upgrading lock, even with low_priority_updates

The problem is that there is no mechanism to control whether a
delayed insert takes a high or low priority lock on a table.

The solution is to modify the delayed insert thread ("handler")
to take into account the global value of low_priority_updates
when taking table locks. The value of low_priority_updates is
retrieved when the insert delayed thread is created and will
remain the same for the duration of the thread.
This commit is contained in:
Davi Arnaut
2009-02-03 15:16:24 -02:00
parent 6fb2ba1c3d
commit bc03c9ef19
5 changed files with 81 additions and 5 deletions
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9
mysys/thr_lock.c
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@@ -1359,7 +1359,8 @@ void thr_downgrade_write_lock(THR_LOCK_DATA *in_data,
/* Upgrade a WRITE_DELAY lock to a WRITE_LOCK */
my_bool thr_upgrade_write_delay_lock(THR_LOCK_DATA *data)
my_bool thr_upgrade_write_delay_lock(THR_LOCK_DATA *data,
enum thr_lock_type new_lock_type)
{
THR_LOCK *lock=data->lock;
DBUG_ENTER("thr_upgrade_write_delay_lock");
@@ -1372,7 +1373,7 @@ my_bool thr_upgrade_write_delay_lock(THR_LOCK_DATA *data)
}
check_locks(lock,"before upgrading lock",0);
/* TODO: Upgrade to TL_WRITE_CONCURRENT_INSERT in some cases */
data->type=TL_WRITE; /* Upgrade lock */
data->type= new_lock_type; /* Upgrade lock */
/* Check if someone has given us the lock */
if (!data->cond)
@@ -1411,6 +1412,7 @@ my_bool thr_upgrade_write_delay_lock(THR_LOCK_DATA *data)
my_bool thr_reschedule_write_lock(THR_LOCK_DATA *data)
{
THR_LOCK *lock=data->lock;
enum thr_lock_type write_lock_type;
DBUG_ENTER("thr_reschedule_write_lock");
pthread_mutex_lock(&lock->mutex);
@@ -1420,6 +1422,7 @@ my_bool thr_reschedule_write_lock(THR_LOCK_DATA *data)
DBUG_RETURN(0);
}
write_lock_type= data->type;
data->type=TL_WRITE_DELAYED;
if (lock->update_status)
(*lock->update_status)(data->status_param);
@@ -1438,7 +1441,7 @@ my_bool thr_reschedule_write_lock(THR_LOCK_DATA *data)
free_all_read_locks(lock,0);
pthread_mutex_unlock(&lock->mutex);
DBUG_RETURN(thr_upgrade_write_delay_lock(data));
DBUG_RETURN(thr_upgrade_write_delay_lock(data, write_lock_type));
}