[ale] mysql and high load levels

djinn at djinnspace.com djinn at djinnspace.com
Mon Sep 10 22:29:22 EDT 2001


Well, someone on the mysql list is having the exact same problem as I, with the
exact same setup (apache 1.3.20 + php4.0.6 + mysql 3.23.41)...but he's running
2.2.19.  Now I realise that 2.2.19 and 2.4 may have a good bit in common since
they were developed more or less concurrently...I'm beginning to wonder if its
not a PHP + shiny new mysql problem.  I tried backing off a couple versions of
mysql with no results, but I may take it back further to the one I was running
successfully...that will help determine if its kernel or mysql.    Since I'm not
anywhere near my machines, and since I've been having so many problems lately,
I'd rather not reboot with a new kernel unless I absolutely have to.

Top shows kswapd wayyyy down the list and my memory seems to be...well...it
hovers between 85 and 95% but I can tackle that later  (the board on this system
won't hold more than 512MB...this is a replacement for the system that died ...
it has not been my week).
Mysqld, on the other hand, is at the top of the list, jumping between 30 and 40%
cpu utilization and 3 and 4%.  Sar shows the same thing.  During a load level
spike, mysqld takes over 100% cpu utilization and seems to spawn processes...

I've been monitoring the system by just letting
while true; do w |head -1; ps -ef |wc -l; sleep 10; done
scroll up a window all day, so that if anything happens I can catch it and
restart mysqld before it goes ballistic...and the ps count seems to go up with
the load level.  I don't know if that's a "feature" of mysql... all the processes
except what is normal to a stripped, sleeping system (all but 39 processes)
belong to mysql.

Thanks for the help!!

jenn,
reconsidering my choice in career ;)

Joseph Andrew Knapka wrote:

> Jeff Hubbs wrote:
> >
> > Jenn -
> >
> > If it were me - and please understand that I have very, very little
> > experience with MySQL - but I'd try going back to a 2.2 kernel first.
>
> Seconded (including the disclaimer :-). There seem to be a number of
> ways the 2.4 kernels can snafu WRT memory management. When your load
> goes up, what process(es) are using all that CPU? I'll place a small
> wager on kswapd.
>
> Cheers,
>
> --
> # Joe Knapka
> # "You know how many remote castles there are along the
> #  gorges? You can't MOVE for remote castles!" - Lu Tze re. Uberwald
> # Linux MM docs:
> http://home.earthlink.net/~jknapka/linux-mm/vmoutline.html
> --
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