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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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14
sql/sql_base.cc
View File

@ -530,7 +530,7 @@ void close_thread_tables(THD *thd, bool lock_in_use, bool skip_derived)
if (found_old_table)
{
/* Tell threads waiting for refresh that something has happened */
VOID(pthread_cond_broadcast(&COND_refresh));
broadcast_refresh();
}
if (!lock_in_use)
VOID(pthread_mutex_unlock(&LOCK_open));
@ -1035,7 +1035,7 @@ TABLE *unlink_open_table(THD *thd, TABLE *list, TABLE *find)
}
*prev=0;
// Notify any 'refresh' threads
pthread_cond_broadcast(&COND_refresh);
broadcast_refresh();
return start;
}
@ -1577,7 +1577,7 @@ bool reopen_table(TABLE *table,bool locked)
if (table->triggers)
table->triggers->set_table(table);
VOID(pthread_cond_broadcast(&COND_refresh));
broadcast_refresh();
error=0;
end:
@ -1678,7 +1678,7 @@ bool reopen_tables(THD *thd,bool get_locks,bool in_refresh)
{
my_afree((gptr) tables);
}
VOID(pthread_cond_broadcast(&COND_refresh)); // Signal to refresh
broadcast_refresh();
*prev=0;
DBUG_RETURN(error);
}
@ -1715,7 +1715,7 @@ void close_old_data_files(THD *thd, TABLE *table, bool abort_locks,
}
}
if (found)
VOID(pthread_cond_broadcast(&COND_refresh)); // Signal to refresh
broadcast_refresh();
DBUG_VOID_RETURN;
}
@ -1807,7 +1807,7 @@ bool drop_locked_tables(THD *thd,const char *db, const char *table_name)
}
*prev=0;
if (found)
VOID(pthread_cond_broadcast(&COND_refresh)); // Signal to refresh
broadcast_refresh();
if (thd->locked_tables && thd->locked_tables->table_count == 0)
{
my_free((gptr) thd->locked_tables,MYF(0));
@ -5249,7 +5249,7 @@ bool remove_table_from_cache(THD *thd, const char *db, const char *table_name,
Signal any thread waiting for tables to be freed to
reopen their tables
*/
(void) pthread_cond_broadcast(&COND_refresh);
broadcast_refresh();
DBUG_PRINT("info", ("Waiting for refresh signal"));
if (!(flags & RTFC_CHECK_KILLED_FLAG) || !thd->killed)
{