[MDEV-12531] TIme column in SHOW PROCESSLIST shows NULL for InnoDB service threads Created: 2017-04-19  Updated: 2020-03-25  Resolved: 2020-03-25

Status: Closed
Project: MariaDB Server
Component/s: Admin statements, Storage Engine - InnoDB
Affects Version/s: 10.2
Fix Version/s: 10.5.1

Type: Bug Priority: Major
Reporter: Elena Stepanova Assignee: Vladislav Vaintroub
Resolution: Fixed Votes: 1
Labels: None

Issue Links:
Relates
relates to MDEV-11703 InnoDB background threads show up in ... Stalled
relates to MDEV-16264 Implement a common work queue for Inn... Closed

 Description   

MariaDB [(none)]> show processlist;
+----+-------------+-----------------+------+---------+------+--------------------------+------------------+----------+
| Id | User        | Host            | db   | Command | Time | State                    | Info             | Progress |
+----+-------------+-----------------+------+---------+------+--------------------------+------------------+----------+
|  1 | system user |                 | NULL | Daemon  | NULL | InnoDB purge worker      | NULL             |    0.000 |
|  2 | system user |                 | NULL | Daemon  | NULL | InnoDB purge worker      | NULL             |    0.000 |
|  4 | system user |                 | NULL | Daemon  | NULL | InnoDB purge coordinator | NULL             |    0.000 |
|  3 | system user |                 | NULL | Daemon  | NULL | InnoDB purge worker      | NULL             |    0.000 |
|  5 | system user |                 | NULL | Daemon  | NULL | InnoDB shutdown handler  | NULL             |    0.000 |
|  9 | root        | localhost:55630 | NULL | Query   |    0 | init                     | show processlist |    0.000 |
| 10 | root        | localhost:55632 | NULL | Sleep   |   12 |                          | NULL             |    0.000 |
+----+-------------+-----------------+------+---------+------+--------------------------+------------------+----------+

Time NULL instead of a numeric value breaks third-party tools, such as pt* toolkit, see https://bugs.launchpad.net/percona-toolkit/+bug/1680803 . Every individual tool should be easy to fix, but it doesn't make sense to bother, better just to show there something tool-friendly.

SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST already shows zeros:

*************************** 7. row ***************************
           ID: 1
         USER: system user
         HOST: 
           DB: NULL
      COMMAND: Daemon
         TIME: 0
        STATE: InnoDB purge worker
         INFO: NULL
      TIME_MS: 0.000
        STAGE: 0
    MAX_STAGE: 0
     PROGRESS: 0.000
  MEMORY_USED: 24592
EXAMINED_ROWS: 0
     QUERY_ID: 0
  INFO_BINARY: NULL
          TID: 11765
7 rows in set (0.01 sec)



 Comments   
Comment by Marko Mäkelä [ 2019-09-30 ]

I think that MDEV-16264 should address this by eliminating most of the InnoDB service threads.

Comment by Vladislav Vaintroub [ 2020-03-25 ]

10.5 eliminated service threads in innodb.
I do not think we should be doing anything in 10.2-10.4

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