| Bug #25042 | OPTIMIZE TABLE cause race condition in IO CACHE SHARE | ||
|---|---|---|---|
| Submitted: | 13 Dec 2006 15:15 | Modified: | 30 Mar 2007 19:37 |
| Reporter: | Kristofer Pettersson | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server | Severity: | S2 (Serious) |
| Version: | 5.0.15/5.0BK/5.1BK | OS: | Windows (Windows (XP)) |
| Assigned to: | Kristofer Pettersson | CPU Architecture: | Any |
[16 Dec 2006 11:35]
Kristofer Pettersson
Test that causes dead lock on windows XP when run from mtr
Attachment: myisam2.test (application/octet-stream, text), 1.62 KiB.
[17 Jan 2007 12:16]
Kristofer Pettersson
Duplicate of http://bugs.mysql.com/bug.php?id=24685
[26 Jan 2007 13:26]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/18852 ChangeSet@1.2353, 2007-01-26 13:54:11+01:00, Kristofer.Pettersson@naruto. +2 -0 Bug#25042 OPTIMIZE TABLE cause race condition in IO CACHE SHARE - The condition variable implementation "lost" a signal to WaitOnSingleObject when a semaphore was released. - The signal could be consumed by a new call to pthread_cond_wait before all waiting threads had awoken. - The new implementation of pthread_cond_* uses events instead of semaphores. It also uses an extra lock to protect entry into a new cond wait before the broadcast has finished.
[15 Feb 2007 13:38]
Kristofer Pettersson
Laterst change set_ http://lists.mysql.com/commits/19941
[9 Mar 2007 10:51]
Kristofer Pettersson
Pushed to BK-5.0-maint, BK-5.1-maint, BK-5.1-runtime.
[14 Mar 2007 17:47]
Ingo Strüwing
According to my findings the patch seems to be in the 5.1 main tree, versions 5.1.16. But I do not see it in the 4.1 or 5.0 main trees.
[22 Mar 2007 20:35]
Mads Martin Joergensen
Fixed in 5.0.40
[30 Mar 2007 19:37]
Paul DuBois
Noted in 5.0.40, 5.1.16 changelogs. OPTIMIZE TABLE caused a race condition in the I/O cache.
[10 Aug 2007 5:41]
JinRong Ye
It still exists in version 5.0.45 under centos 5 64bit or freebsd 6.2 32bit
[10 Aug 2007 6:36]
JinRong Ye
when the set myisam_repair_threads = 1 mysql>repair table cdb_posts; +-----------------+--------+----------+----------+ | Table | Op | Msg_type | Msg_text | +-----------------+--------+----------+----------+ | Forum.cdb_posts | repair | status | OK | +-----------------+--------+----------+----------+ 1 row in set (1 min 14.30 sec) but when the set myisam_repair_threads = 2 (or more, for example: 10) mysql>show processlist; +----+------+-----------+-------+---------+------+-----------------------+------------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+-------+---------+------+-----------------------+------------------------+ | 1 | root | localhost | Forum | Query | 1330 | Repair with 7 threads | repair table cdb_posts | | 2 | root | localhost | Forum | Query | 0 | NULL | show processlist | +----+------+-----------+-------+---------+------+-----------------------+------------------------+ mysql>select version(); +------------+ | version() | +------------+ | 5.0.45-log | +------------+ the table `cdb_posts` has 883671 rows，and 7 indexes; under the FreeBSD 6.2 64bit/32bit or CentOS 5 64bit OS
Description: When optimizing a MySQL table I get a very probable dead lock in the io cache code on windows XP and a BK-clone from the maint-tree. The test is repeatable with the below test case (which also is found in myisam.test) when runned from mysql-test-run. With the --debug option I'm much less likely to dead lock as I can't repeat it. At dead lock: 5180 __tmainCRTStartup pthread_cond_wait 4560 _callthreadstart handle_shutdown 6000 _callthreadstart pthread_cond_timedwait 3968 _callthreadstart _beginthread (mi_repair_parallel) _callthreadstart pthread_cond_wait (thr_find_all_keys) _callthreadstart pthread_cond_wait (thr_find_all_keys) _callthreadstart pthread_cond_wait The (thr_find_all_keys)-threads are halted in the lock_io_cache function: **Thread 1: while ((!cshare->read_end || (cshare->pos_in_file < pos)) && cshare->source_cache) { DBUG_PRINT("io_cache_share", ("reader waits in lock")); pthread_cond_wait(&cshare->cond, &cshare->mutex); } **Thread 2: while ((!cshare->read_end || (cshare->pos_in_file < pos)) && cshare->running_threads) { DBUG_PRINT("io_cache_share", ("reader waits in lock")); pthread_cond_wait(&cshare->cond, &cshare->mutex); } How to repeat: # Test OPTIMIZE. This creates a new data file. CREATE TABLE t1 ( `_id` int(11) NOT NULL default '0', `url` text, `email` text, `description` text, `loverlap` int(11) default NULL, `roverlap` int(11) default NULL, `lneighbor_id` int(11) default NULL, `rneighbor_id` int(11) default NULL, `length_` int(11) default NULL, `sequence` mediumtext, `name` text, `_obj_class` text NOT NULL, PRIMARY KEY (`_id`), UNIQUE KEY `sequence_name_index` (`name`(50)), KEY (`length_`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1; # INSERT INTO t1 VALUES (1,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample1',''), (2,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample2',''), (3,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample3',''), (4,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample4',''), (5,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample5',''), (6,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample6',''), (7,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample7',''), (8,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample8',''), (9,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'sample9',''); # SELECT _id FROM t1; DELETE FROM t1 WHERE _id < 8; --replace_column 6 # 7 # 8 # 9 # 11 # 12 # 13 # 14 # 15 # 16 # SHOW TABLE STATUS LIKE 't1'; CHECK TABLE t1 EXTENDED; OPTIMIZE TABLE t1; CHECK TABLE t1 EXTENDED; --replace_column 6 # 7 # 8 # 9 # 11 # 12 # 13 # 14 # 15 # 16 # SHOW TABLE STATUS LIKE 't1'; SELECT _id FROM t1; DROP TABLE t1;