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BUG#12574820: binlog.binlog_tmp_table timing out in daily and weekly trunk run

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Problem: MYSQL_BIN_LOG::reset_logs acquires mutexes in wrong order.
The correct order is first LOCK_thread_count and then LOCK_log. This function
does it the other way around. This leads to deadlock when run in parallel
with a thread that takes the two locks in correct order. For example, a thread
that disconnects will take the locks in the correct order.
Fix: change order of the locks in MYSQL_BIN_LOG::reset_logs:
first LOCK_thread_count and then LOCK_log.
This commit is contained in:
Sven Sandberg 2011-05-26 12:50:43 +02:00
parent aa0c8235a4
commit b76c277a8f
4 changed files with 41 additions and 7 deletions
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1
mysql-test/suite/binlog/r/binlog_reset_master.result Normal file
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@ -0,0 +1 @@
RESET MASTER;

26
mysql-test/suite/binlog/t/binlog_reset_master.test Normal file
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@ -0,0 +1,26 @@
# ==== Purpose ====
#
# Test bugs in RESET MASTER.
--source include/have_debug.inc
--source include/have_log_bin.inc
#######################################################################
# BUG#12574820: binlog.binlog_tmp_table timing out in daily and weekly trunk run
# Problem: MYSQL_BIN_LOG::reset_logs acquired LOCK_thread_count and
# LOCK_log in the wrong order. This could cause a deadlock when
# RESET MASTER was run concurrently with a disconnecting thread.
#######################################################################
# We use sleep, not debug_sync, because the sync point needs to be in
# the thread shut down code after the debug sync facility has been
# shut down.
--let $write_var= SET DEBUG="+d,sleep_after_lock_thread_count_before_delete_thd"; CREATE TEMPORARY TABLE test.t1 (a INT);
--let $write_to_file= GENERATE
--disable_query_log
--source include/write_var_to_file.inc
--enable_query_log
--exec $MYSQL < $write_to_file
RESET MASTER;
--remove_file $write_to_file

15
sql/log.cc
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@ -2989,12 +2989,6 @@ bool MYSQL_BIN_LOG::reset_logs(THD* thd)
DBUG_ENTER("reset_logs");
ha_reset_logs(thd);
/*
We need to get both locks to be sure that no one is trying to
write to the index log file.
*/
pthread_mutex_lock(&LOCK_log);
pthread_mutex_lock(&LOCK_index);
/*
The following mutex is needed to ensure that no threads call
@ -3002,7 +2996,14 @@ bool MYSQL_BIN_LOG::reset_logs(THD* thd)
thread. If the transaction involved MyISAM tables, it should go
into binlog even on rollback.
*/
VOID(pthread_mutex_lock(&LOCK_thread_count));
pthread_mutex_lock(&LOCK_thread_count);
/*
We need to get both locks to be sure that no one is trying to
write to the index log file.
*/
pthread_mutex_lock(&LOCK_log);
pthread_mutex_lock(&LOCK_index);
/* Save variables so that we can reopen the log */
save_name=name;

6
sql/mysqld.cc
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@ -1903,6 +1903,12 @@ void unlink_thd(THD *thd)
pthread_mutex_unlock(&LOCK_connection_count);
(void) pthread_mutex_lock(&LOCK_thread_count);
/*
Used by binlog_reset_master. It would be cleaner to use
DEBUG_SYNC here, but that's not possible because the THD's debug
sync feature has been shut down at this point.
*/
DBUG_EXECUTE_IF("sleep_after_lock_thread_count_before_delete_thd", sleep(5););
thread_count--;
delete thd;
DBUG_VOID_RETURN;