[MDEV-14550] Error log flood : "InnoDB: page_cleaner: 1000ms intended loop took N ms. The settings might not be optimal." Created: 2017-11-30  Updated: 2022-04-26  Resolved: 2018-06-19

Status: Closed
Project: MariaDB Server
Component/s: Storage Engine - InnoDB
Affects Version/s: 10.2
Fix Version/s: 10.2.12, 10.3.3

Type: Bug Priority: Major
Reporter: Vladislav Vaintroub Assignee: Marko Mäkelä
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Relates
relates to MDEV-13670 [Note] InnoDB: page_cleaner: 1000ms i... Closed
relates to MDEV-16526 Overhaul the InnoDB page flushing Closed
relates to MDEV-23399 10.5 performance regression with IO-b... Closed
relates to MDEV-27466 Deadlock when purge thread races the ... Closed
relates to MDEV-28415 ALTER TABLE on a large table hangs In... Closed

 Description   

There are too many messages in form
"InnoDB: page_cleaner: 1000ms intended loop took 4450ms. The settings might not be optimal".

An example of the flood is here https://jira.mariadb.org/secure/attachmentzip/unzip/64627/44712%5B0%5D/

A message like this is written every 15 seconds.
A better idea is to write only seldomly. If this is something performance related, you can expose the average slowness via status variable or something like that.

 Comments   
Comment by Marko Mäkelä [ 2018-06-19 ]

The message was hidden at the default log_warnings level (2 or less). The actual problem will be addressed in MDEV-16526.

Comment by Marko Mäkelä [ 2020-09-15 ]

While working on MDEV-23399, I found a likely explanation for these messages. The ‘flush_list flushing’ would actually wait for buffer pool page latches, and therefore a single batch can take an arbitrarily long time.

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