Bug #85747 Documentation on MTS statistics
Submitted: 31 Mar 2017 16:12 Modified: 26 Apr 2017 12:02
Reporter: Juan Arruti Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: Replication Severity:S3 (Non-critical)
Version:5.7, 5.7.18 OS:Any
Assigned to: CPU Architecture:Any

[31 Mar 2017 16:12] Juan Arruti
Description:
Hi,

I didn't find information in MySQL reference manual about MTS statistics, I had to look into source code in order to get more information about them. Please add information to manual to get a better understanding about the meaning of each statistic and information about how to disable statistics messages from error log.

Thanks

How to repeat:
When using a multi-threaded slave, slave_parallel_workers greater than 0, and log_warnings > 1 or log_error_verbosity > 2, statistics from MTS are shown almost every 120 seconds in error log file, as follows:

2017-03-31T00:48:32.305882Z 2 [Note] Multi-threaded slave statistics for channel '': seconds elapsed = 19364; events assigned = 124929; worker queues filled over overrun level = 0; waited due a Worker queue full = 0; waited due the total size = 0; waited at clock conflicts = 0 waited (count) when Workers occupied = 0 waited when Workers occupied = 0

2017-03-31T00:56:40.471525Z 2 [Note] Multi-threaded slave statistics for channel '': seconds elapsed = 488; events assigned = 139265; worker queues filled over overrun level = 0; waited due a Worker queue full = 0; waited due the total size = 0; waited at clock conflicts = 0 waited (count) when Workers occupied = 0 waited when Workers occupied = 0
[26 Apr 2017 12:02] Umesh Shastry
Hello Juan Arruti,

Thank you for the report and feedback.
Verifying as code bug after discussing internally with Developer.

Thanks,
Umesh
[30 Oct 2017 10:34] Umesh Shastry
Bug #88251 marked as duplicate of this one