Re: Dramatic mysqld slowness when running compiles in parallel

[Andrew Doran <ad%netbsd.org@localhost>]

On Mon, Oct 06, 2008 at 04:42:58PM -0600, Sverre Froyen wrote:

> On Monday 06 October 2008, Andrew Doran wrote:
> > What happens with 'skip-thread-priority' in my.cnf?
> 
> With this option, the slowdown is almost eliminated.  I can still observe 
> occasional delays but they are of the order of a second not ten seconds or 
> more.  I probably would never have noticed the issue if I had used this 
> option earlier.

It's a bug in MySQL. Look at the PRI column in the top output and notice
that many of the MySQL threads have very low priority, meaning that they'll
only run when the system is ~idle. I think someone was going to file a bug
report with the MySQL people but I don't know if that ever happened. We
should at least disable this in pkgsrc.

        http://bugs.mysql.com/bug.php?id=18526

You won't notice this problem with NetBSD 4.0 or revivesa because neither
is realtime capable.

Andrew