[MDEV-6832] ER_LOCK_WAIT_TIMEOUT on SHOW STATUS Created: 2014-10-03  Updated: 2015-02-17  Resolved: 2015-01-01

Status: Closed
Project: MariaDB Server
Component/s: wsrep
Affects Version/s: 5.5.40-galera, 10.0.15-galera
Fix Version/s: 5.5.41-galera, 10.0.16-galera

Type: Bug Priority: Major
Reporter: Nirbhay Choubey (Inactive) Assignee: Nirbhay Choubey (Inactive)
Resolution: Fixed Votes: 1
Labels: None


 Description   

Start a node with wsrep provider and wsrep_causal_reads=ON and then execute the following commands :

MariaDB [test]> show status like 'wsrep_ready';
 
+---------------+-------+
 
| Variable_name | Value |
 
+---------------+-------+
 
| wsrep_ready   | ON    |
 
+---------------+-------+
 
1 row in set (0.64 sec)
 
 
 
MariaDB [test]> set global wsrep_provider="/usr/lib/galera/libgalera_smm.so";
 
Query OK, 0 rows affected (2.42 sec)
 
 
 
MariaDB [test]> show status like 'wsrep_ready';
 
ERROR 1205 (HY000): Lock wait timeout exceeded; try restarting transaction
 
 



 Comments   
Comment by Nirbhay Choubey (Inactive) [ 2014-12-25 ]

http://lists.askmonty.org/pipermail/commits/2014-December/007214.html

Comment by Jan Lindström (Inactive) [ 2014-12-28 ]

Only one small question, why call mtr.add_suppression("safe_mutex: Found wrong usage of mutex.*"); is needed ? Sounds like a bug.

R: Jan

Comment by Nirbhay Choubey (Inactive) [ 2014-12-29 ]

Its because in wsrep_cluster_address_update LOCK_global_system_variables is released
temporarily during closure of client connections.

  /* stop replication is heavy operation, and includes closing all client $
 
     connections. Closing clients may need to get LOCK_global_system_variables$
 
     at least in MariaDB.$
 
$ 
     Note: releasing LOCK_global_system_variables may cause race condition, if $
 
     there can be several concurrent clients changing wsrep_provider$
 
  */$
 
  mysql_mutex_unlock(&LOCK_global_system_variables);$
 
  wsrep_stop_replication(thd);$
 
  mysql_mutex_lock(&LOCK_global_system_variables);$

I will check further is this is really needed here and remove if not.

Comment by Nirbhay Choubey (Inactive) [ 2014-12-30 ]

http://lists.askmonty.org/pipermail/commits/2014-December/007223.html

Comment by Jan Lindström (Inactive) [ 2014-12-30 ]

ok to push.

Comment by Nirbhay Choubey (Inactive) [ 2015-01-01 ]

http://bazaar.launchpad.net/~maria-captains/maria/maria-5.5-galera/revision/3551
http://bazaar.launchpad.net/~maria-captains/maria/maria-10.0-galera/revision/3909

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