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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.


include/thr_lock.h:
  Update prototype.
mysql-test/r/delayed.result:
  Add test case result for Bug#40536
mysql-test/t/delayed.test:
  Add test case for Bug#40536
mysys/thr_lock.c:
  Add function parameter which specifies the write lock type.
sql/sql_insert.cc:
  Take a low priority write lock if global value of low_priority_updates
  was ON when the thread was created.
This commit is contained in:
Davi Arnaut
2009-02-03 15:16:24 -02:00
parent a07a7afefa
commit c9dc936a2b
5 changed files with 81 additions and 5 deletions
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5
sql/sql_insert.cc
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@@ -1690,6 +1690,7 @@ public:
class Delayed_insert :public ilink {
uint locks_in_memory;
thr_lock_type delayed_lock;
public:
THD thd;
TABLE *table;
@@ -1731,6 +1732,8 @@ public:
pthread_cond_init(&cond_client,NULL);
VOID(pthread_mutex_lock(&LOCK_thread_count));
delayed_insert_threads++;
delayed_lock= global_system_variables.low_priority_updates ?
TL_WRITE_LOW_PRIORITY : TL_WRITE;
VOID(pthread_mutex_unlock(&LOCK_thread_count));
}
~Delayed_insert()
@@ -2540,7 +2543,7 @@ bool Delayed_insert::handle_inserts(void)
table->use_all_columns();
thd_proc_info(&thd, "upgrading lock");
if (thr_upgrade_write_delay_lock(*thd.lock->locks))
if (thr_upgrade_write_delay_lock(*thd.lock->locks, delayed_lock))
{
/*
This can happen if thread is killed either by a shutdown