Bug #98434 Replication threads not instrumented in perfschema for variables
Submitted: 30 Jan 2020 0:13 Modified: 12 Jan 2021 9:11
Reporter: Manuel Ung Email Updates:
Status: Duplicate Impact on me:
None 
Category:MySQL Server: Performance Schema Severity:S3 (Non-critical)
Version:8.0.19, 5.7.29 OS:Any
Assigned to: Marc ALFF CPU Architecture:Any

[30 Jan 2020 0:13] Manuel Ung
Description:
The variables_by_thread perfschema table does not show slave threads at all.

How to repeat:
Connect to a slave, and find that this query returns empty results:

use performance_schema;
select * from threads, variables_by_thread where name like '%slave%' and threads.thread_id = variables_by_thread.thread_id;

Suggested fix:
When initializing slave threads, we need a call to mysql_thread_set_psi_THD to attach the THD.
[30 Jan 2020 5:36] MySQL Verification Team
Hello Manuel Ung,

Thank you for the bug report and feedback.

regards,
Umesh
[12 Jan 2021 9:11] Marc ALFF
Fixed by the related contribution:

Bug #102115 	Contribution by Facebook: Fix replica threads not showing in variables_by_thread

Closing this bug.