Bug #21256 SET GLOBAL query_cache_size = <non-zero> crashes the server under heavy load
Submitted: 24 Jul 2006 16:52 Modified: 26 Jan 2007 9:59
Reporter: Tomash Brechko Email Updates:
Status: Can't repeat Impact on me:
None 
Category:MySQL Server Severity:S2 (Serious)
Version:5.0.25-BK OS:Linux (Linux FC3)
Assigned to: CPU Architecture:Any

[24 Jul 2006 16:52] Tomash Brechko 
Description:
Issuing SET GLOBAL query_cache_size = <non-zero> (when it was zero) craches the server if it is under heavy load.

How to repeat:
While running conc_sys suite (or other heavy load task), connect to the server and do

  SET GLOBAL query_cache_size = 1024*1024*1024;

I experience the crash every time I do that.

Suggested fix:
The crash happens somewhere inside the malloc() call from the thread other then the one issuing a command.
[22 Aug 2006 14:30] MySQL Verification Team 
I couldn't repeat using mysql-standard-5.0.24-linux-i686-glibc23
NExt, I will try a recent debug build of 5.0-bk, and post the results here.
[24 Aug 2006 8:01] Tonci Grgin 
Tomash, as you can see, Shane and Sveta can't repeat the crash.
[21 Oct 2006 19:37] MySQL Verification Team 
marking as a duplicate of bug #23527
[26 Jan 2007 9:59] Tomash Brechko 
Setting back to "Can't repeat", as this bug is not a duplicate of bug#23527, because the latter was introduced with the fix of bug#21051, and this bug was reported before that.