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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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9
sql/sql_table.cc
View File

@@ -1674,8 +1674,6 @@ bool mysql_create_table(THD *thd,const char *db, const char *table_name,
my_error(ER_TABLE_EXISTS_ERROR, MYF(0), alias);
DBUG_RETURN(TRUE);
}
if (wait_if_global_read_lock(thd, 0, 1))
DBUG_RETURN(TRUE);
VOID(pthread_mutex_lock(&LOCK_open));
if (!internal_tmp_table && !(create_info->options & HA_LEX_CREATE_TMP_TABLE))
{
@@ -1743,7 +1741,6 @@ bool mysql_create_table(THD *thd,const char *db, const char *table_name,
end:
VOID(pthread_mutex_unlock(&LOCK_open));
start_waiting_global_read_lock(thd);
thd->proc_info="After create";
DBUG_RETURN(error);
@@ -1923,7 +1920,7 @@ void close_cached_table(THD *thd, TABLE *table)
thd->open_tables=unlink_open_table(thd,thd->open_tables,table);
/* When lock on LOCK_open is freed other threads can continue */
pthread_cond_broadcast(&COND_refresh);
broadcast_refresh();
DBUG_VOID_RETURN;
}
@@ -3894,7 +3891,7 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
if (error)
{
VOID(pthread_mutex_unlock(&LOCK_open));
VOID(pthread_cond_broadcast(&COND_refresh));
broadcast_refresh();
goto err;
}
thd->proc_info="end";
@@ -3904,7 +3901,7 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
Query_log_event qinfo(thd, thd->query, thd->query_length, FALSE, FALSE);
mysql_bin_log.write(&qinfo);
}
VOID(pthread_cond_broadcast(&COND_refresh));
broadcast_refresh();
VOID(pthread_mutex_unlock(&LOCK_open));
#ifdef HAVE_BERKELEY_DB
if (old_db_type == DB_TYPE_BERKELEY_DB)