Bug #59443 query_cache_debug.test is occasionally very slow
Submitted: 12 Jan 2011 12:03 Modified: 31 May 2011 19:23
Reporter: Jon Olav Hauglid Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Tests Severity:S3 (Non-critical)
Version:5.5+ OS:Any
Assigned to: CPU Architecture:Any
Triage: Triaged: D3 (Medium)

[12 Jan 2011 12:03] Jon Olav Hauglid
Description:
The query_cache_debug MTR test usually takes less than 100 ms to run.
But occasionally it takes more than 300 seconds. This is pretty annoying
when running the test suite.

Example MTR output:
main.query_cache_debug                   [ pass ]     82
main.query_cache_debug                   [ pass ]     86
main.query_cache_debug                   [ pass ]     87
main.query_cache_debug                   [ pass ]  300084
main.query_cache_debug                   [ pass ]     88
main.query_cache_debug                   [ pass ]     87

How to repeat:
./mtr --mem query_cache_debug --repeat=100

Seems more likely to happen if the machine has high load than if it is otherwise idle.
I've only seen this on 5.5 and trunk, not on 5.1.

Suggested fix:
n/a
[31 May 2011 19:23] Paul Dubois
Changes to test suite. No changelog entry needed.