Comments on: MySQL 4 to MySQL 5 Upgrade performance regressions

By: Nick

Nick — Wed, 12 Aug 2009 15:24:43 +0000

I am seeing the same thing on 5.0.45 on redhat-linux.
Two consecutive “processlist” one second apart shows only one thread (An UPDATE) — and it is apparently stuck in the “end” state.
Is there a way to get more insight into what is happening inside mysql?
It really acts like the thread is going to sleep for a long time awaiting completion of something… but one second is a long time and the server isn’t particularly busy.

By: Baron Schwartz

Baron Schwartz — Mon, 15 Jun 2009 16:56:50 +0000

Here is a roadmap for a tool to help discover these issues before they are a problem: http://code.google.com/p/maatkit/wiki/mk_upgrade

By: Rolf

Rolf — Mon, 15 Jun 2009 16:20:15 +0000

I’ve a problem with similar symptoms that you describe in this blog entry. My MySQL version is 5.0.27. A few times a day MySQL hangs. In the process list I see some update statements in the ‘end state’, often I also see a commit statement. This statments need about 1 min to execute. In the meantime the process list grows an all statments are blocked from executing (time column increasing). As soon the update or commit statment is finished, all the ‘queued’ statements are finally executed.

I’m not sure if this is the same problem, as I can not imagine that it takes such a long time to write the logs to disk (up to 1 min).
Do you have any suggestion where to look? Are there other possible problems in the commit phase of a transaction.

BTW. The applications uses mostly autocommit statments, something that I can not easily change.

Thanks for any help

By: peter

peter — Mon, 11 Jun 2007 18:36:39 +0000

Group commit was in MySQL since Innodb was added to it so it is available in any MySQL 4.1 version.

By: mfc

mfc — Sun, 10 Jun 2007 15:31:54 +0000

Hi,

What version of 4.1 did group commit first show up in?

Thanks,

Mike

By: peter

peter — Sat, 09 Jun 2007 15:05:58 +0000

Sergey,

Thank you for info. From my standpoint it does not matter if this is Innodb or MySQL part of the code. Innodb is officially supported by MySQL and it was MySQL task to ensure there are no regressions in 5.0 Plus it surely does not help this issue is not properly described in upgrade notes.

By: manoj

manoj — Fri, 08 Jun 2007 14:04:07 +0000

replication not working when installed mysql 5 in rhel as4

By: Sergei Golubchik

Sergei Golubchik — Thu, 07 Jun 2007 08:25:56 +0000

Just FYI. This was discussed more than once. But the agreement was that this is internal InnoDB issue, it can and should be fixed in the InnoDB. Other storage engines have completely automatic group commit that doesn’t need any hooks in the binlog code. Heikki agrees, by the way, and the solution is known. The priority isn’t high, though.