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Bug#16986 - Deadlock condition with MyISAM tables

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Addendum fixes after changing the condition variable
for the global read lock.

The stress test suite revealed some deadlocks. Some were
related to the new condition variable (COND_global_read_lock)
and some were general problems with the global read lock.

It is now necessary to signal COND_global_read_lock whenever 
COND_refresh is signalled.

We need to wait for the release of a global read lock if one 
is set before every operation that requires a write lock.
But we must not wait if we have locked tables by LOCK TABLES.
After setting a global read lock a thread waits until all
write locks are released.
This commit is contained in:
ingo@mysql.com
2006-06-26 19:14:35 +02:00
parent fa98891ee7
commit d27a15a81c
10 changed files with 208 additions and 66 deletions
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11
sql/sql_handler.cc
View File

@ -254,7 +254,8 @@ err:
DESCRIPTION
Though this function takes a list of tables, only the first list entry
will be closed. Broadcasts a COND_refresh condition.
will be closed.
Broadcasts refresh if it closed the table.
RETURN
FALSE ok
@ -291,7 +292,7 @@ bool mysql_ha_close(THD *thd, TABLE_LIST *tables)
if (close_thread_table(thd, table_ptr))
{
/* Tell threads waiting for refresh that something has happened */
VOID(pthread_cond_broadcast(&COND_refresh));
broadcast_refresh();
}
VOID(pthread_mutex_unlock(&LOCK_open));
}
@ -608,7 +609,7 @@ err0:
tables are closed (if MYSQL_HA_FLUSH_ALL) is set.
If 'tables' is NULL and MYSQL_HA_FLUSH_ALL is not set,
all HANDLER tables marked for flush are closed.
Broadcasts a COND_refresh condition, for every table closed.
Broadcasts refresh for every table closed.
NOTE
Since mysql_ha_flush() is called when the base table has to be closed,
@ -704,7 +705,7 @@ int mysql_ha_flush(THD *thd, TABLE_LIST *tables, uint mode_flags,
MYSQL_HA_REOPEN_ON_USAGE mark for reopen.
DESCRIPTION
Broadcasts a COND_refresh condition, for every table closed.
Broadcasts refresh if it closed the table.
The caller must lock LOCK_open.
RETURN
@ -742,7 +743,7 @@ static int mysql_ha_flush_table(THD *thd, TABLE **table_ptr, uint mode_flags)
if (close_thread_table(thd, table_ptr))
{
/* Tell threads waiting for refresh that something has happened */
VOID(pthread_cond_broadcast(&COND_refresh));
broadcast_refresh();
}
DBUG_RETURN(0);