[MDEV-30418] Setting wsrep_slave_threads causes thread hang Created: 2023-01-17  Updated: 2023-11-28

Status: Stalled
Project: MariaDB Server
Component/s: wsrep
Affects Version/s: 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 10.10, 10.11, 11.0
Fix Version/s: 10.4, 10.5, 10.6, 10.11

Type: Bug Priority: Critical
Reporter: Roel Van de Paar Assignee: Julius Goryavsky
Resolution: Unresolved Votes: 1
Labels: regression, thread_hang

Issue Links:
Relates
relates to MDEV-25472 Server crashes when wsrep_cluster_add... Closed
relates to MDEV-27689 Node hangs and complete galera cluste... Open

 Description    

SET GLOBAL wsrep_cluster_address=AUTO;
 
SET GLOBAL wsrep_slave_threads=12;

Leads to a thread hang. Another connection will show the hanging statement:

11.0.1 b075191ba8598af6aff5549e6e19f6255aef258a (Optimized)

 
11.0.1-opt>SHOW PROCESSLIST;
 
+----+------+-----------+------+---------+------+----------+-----------------------------------+----------+
 
| Id | User | Host      | db   | Command | Time | State    | Info                              | Progress |
 
+----+------+-----------+------+---------+------+----------+-----------------------------------+----------+
 
|  4 | root | localhost | test | Query   | 7972 | NULL     | SET GLOBAL wsrep_slave_threads=12 |    0.000 |
 
|  5 | root | localhost | test | Query   |    0 | starting | SHOW PROCESSLIST                  |    0.000 |
 
+----+------+-----------+------+---------+------+----------+-----------------------------------+----------+
 
2 rows in set (0.000 sec)



 Comments   
Comment by Roel Van de Paar [ 2023-01-17 ]

Could this be the cause for MDEV-27689?

Comment by Roel Van de Paar [ 2023-01-17 ]

A build from 22/10/22 (10.11, 50c5743adc87e1cdec1431a02558f6540fe5a6d5) hangs also.
However, a build from 22/09/22 (10.11, 49cee4e21a8e3cc0eccff3a6f9e493247344e24f) does not.
And another build from 11/10/22 (10.7, b6ebadaa66ee68b1880c0e10669543d1ba058c18) also doesn't.

As such, the issue seems to have been introduced between the 11th and 22nd of October 2022.

It is a regression, but not recent.

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