Bug #24474 | mysqld-nt.exe seems to leak on query-cache-size=0 and query-cache-type=1 | ||
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Submitted: | 21 Nov 2006 14:28 | Modified: | 29 Mar 2007 19:54 |
Reporter: | Yahoo Serious (Silver Quality Contributor) | Email Updates: | |
Status: | Can't repeat | Impact on me: | |
Category: | MySQL Server | Severity: | S2 (Serious) |
Version: | 4.1.21-community-nt | OS: | Windows (Windows 2000 SP4) |
Assigned to: | MySQL Verification Team | CPU Architecture: | Any |
Tags: | qc |
[21 Nov 2006 14:28]
Yahoo Serious
[23 Nov 2006 18:03]
MySQL Verification Team
Thank you for the bug report. Could you please when the task manager shows the MySQL server process increasing its memory usage, issue and copy here the output of: SHOW STATUS LIKE 'Qcache%'; RESET QUERY CACHE; SHOW STATUS LIKE 'Qcache%'; Thanks in advance.
[24 Nov 2006 12:22]
Yahoo Serious
All values are 0. In the first test SHOW STATUS did reduce the Memory Usage once (not the whole 'leak'-amount though), but I could not reproduce that. Also RESET in the first test run did freeze the leak, but I could only reproduce that once (so I am afraid I forgot to reset my random-seed). If I use the same random-seed for consecutive runs, the Memory Usage does not increase, which may imply (hidden) usage of the query cache?! The queries I use are: 1. One query to randomly select some placenames SELECT * FROM (SELECT DISTINCT PlaceNameId FROM runtimestreetphrases GROUP BY PlaceNameId) AS PlaceNameIds ORDER BY RAND(7) LIMIT 300; 2. N times a query to select all streets per place SELECT * FROM runtimestreetphrases WHERE PlaceNameId = <PlaceNameId> ORDER BY ConceptValue
[16 Jan 2007 0:50]
MySQL Verification Team
Thank you for the bug report.
[2 Feb 2007 10:47]
Yahoo Serious
I think there also is/was a leak in the query cache when it is on (query-cache-size<>0). I am/was hoping that looking at this simpler reported situation (query-cache-size=0) would lead to a fix for both problems. Since you managed to verify the leak for query-cache-size=0, but this does not seem to get fixed yet, maybe you can also reliably (consistently reproducable) verify it for query-cache-size<>0? That looks like an even more serious bug to me. Although I realize this is an old version, I hope you will realize that it is often easier to upgrade to a new minor version than to a new major version (often technically, but mostly 'politically'). So I think (hope) that will be worth the effort of fixing the bug.
[23 Mar 2007 18:20]
Damien Katz
I see no real evidence of a leak here. If there were a leak, we'd see VM growth. We'll reopen if we find more evidence.
[29 Mar 2007 19:54]
Yahoo Serious
I am puzzled: - there should not be any caching, so memory-usage should not change - it was verified, - now you see no memory-usage change? Then, how did one verify without memory-usage-change?! Anyway, in my live situation, it leaks with query-cache-size 0 and query-cache-type ON (as reported), it does not leak with query-cache-size 0and query-cache-type OFF (as reported), so I'll stick to my work-around and hope you can unpuzzle me, and hopefully fix this bug.