[MDEV-22460] safe_mutex: Found wrong usage of mutex 'LOCK_thd_data' and 'THR_LOCK_myisam', server with WSREP hangs Created: 2020-05-04  Updated: 2022-10-11  Resolved: 2022-10-11

Status: Closed
Project: MariaDB Server
Component/s: Galera, Storage Engine - MyISAM, wsrep
Affects Version/s: 10.4, 10.5
Fix Version/s: N/A

Type: Bug Priority: Major
Reporter: Elena Stepanova Assignee: Jan Lindström (Inactive)
Resolution: Cannot Reproduce Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-22154 safe_mutex: Trying to lock mutex at <... Closed
relates to MDEV-22458 Server with WSREP hangs after INSERT,... Closed

 Description   

Note: It is filed separately from MDEV-22458 for the sake of a different mutex combination, specific to MyISAM. The test case has send/reap, and thus may be non-deterministic. The concurrency is added as it seems to be necessary for producing the mutex error message, hang is reproducible without it. I suppose send/reap can be removed from the test case for the regression suite.

--source include/galera_cluster.inc
 
 
 
CREATE TABLE t1 (a INT) ENGINE=MyISAM;
 
 
 
--connect (con1,localhost,root,,test)
 
--let $con1= `SELECT CONNECTION_ID()`
 
 
 
--connection default
 
--send
 
    INSERT INTO t1 VALUES (1),(2),(3),(4);
 
--connection con1
 
    INSERT INTO t1 VALUES (5),(6),(7),(8);
 
--connection default
 
--reap
 
--error ER_TARGET_NOT_EXPLAINABLE
 
eval SHOW EXPLAIN FOR $con1;
 
DROP TABLE t1;
 
--connection con1
 
SELECT 1;
 
 
 
# Cleanup
 
--disconnect con1

Server hangs upon SELECT. The error log shows this:

10.4 7f03a933

 
safe_mutex: Found wrong usage of mutex 'LOCK_thd_data' and 'THR_LOCK_myisam'
 
Mutex currently locked (in reverse order):
 
THR_LOCK_myisam                   /data/src/10.4/storage/myisam/mi_close.c  line 35
 
LOCK_thd_data                     /data/src/10.4/sql/sql_parse.cc  line 9017

Reproducible on 10.4, 10.5.
Not reproducible on 10.3.

 Comments   
Comment by Ramesh Sivaraman [ 2022-02-04 ]

jplindst Could not reproduce safe mutex wrong usage or wsrep SELECT hang issue on latest 10.4 build.

10.4.23 12cad0c3468d734e041d4ef0cd5a26d2a28606fc (Debug)

 
==============================================================================
 
 
 
TEST                                      RESULT   TIME (ms) or COMMENT
 
--------------------------------------------------------------------------
 
 
 
worker[1] Using MTR_BUILD_THREAD 300, with reserved ports 16000..16019
 
connection node_2;
 
connection node_1;
 
CREATE TABLE t1 (a INT) ENGINE=MyISAM;
 
connect  con1,localhost,root,,test;
 
connection default;
 
INSERT INTO t1 VALUES (1),(2),(3),(4);
 
connection con1;
 
INSERT INTO t1 VALUES (5),(6),(7),(8);
 
connection default;
 
SHOW EXPLAIN FOR 17;
 
ERROR HY000: Target is not running an EXPLAINable command
 
DROP TABLE t1;
 
connection con1;
 
SELECT 1;
 
1
 
1
 
disconnect con1;
 
galera.safemutex5 'innodb'               [ pass ]   2037
 
--------------------------------------------------------------------------
 
The servers were restarted 0 times
 
Spent 2.037 of 20 seconds executing testcases
 
 
 
Completed: All 1 tests were successful.

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