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From:Ashish Mukherjee Date:August 21 2010 11:53am
Subject:Re: Responsibilities of the main mysqld thread?
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Couple of thoughts ...

lsof -p <pid of mysql process> may give some clue of what files/tables it's
reading/writing. From that you may be able to deduce something useful.

Check the slow query log and see if any of the queries are CPU-intensive (by
doing an EXPLAIN) and are the bottleneck.

- Ashish

On Fri, Aug 20, 2010 at 10:09 PM, Tom Kleinpeter <tomkleinpeter@stripped>wrote:

> I've been watching our mysqld procs in htop and the root thread is
> using 75-100% of a CPU most of the time.  I'm trying to understand
> what that is being used for, and so I was hoping someone could tell me
> what that thread does that might be using a lot of CPU.
> We are using 5.5.4-m3, we use MyISAM tables with full text indexes, do
> around 1500-2000 queries per second, accept around 150 connections per
> second, and at the moment both our key cache and our query cache are
> disabled (I was curious if that contention was an issue).  CPU usage
> didn't really change with the caches disabled.
> The server is doing around 2 megabytes of traffic per second.  We
> store a bunch of data compressed, and use "uncompress(columnName)" in
> queries to get it back out.  None of these things set off any red
> flags for me, but it has been a number of years since I've tuned
> MySQL, so I don't really trust myself.
> Thanks,
> Tom
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Responsibilities of the main mysqld thread?Tom Kleinpeter20 Aug
  • Re: Responsibilities of the main mysqld thread?Ashish Mukherjee21 Aug