[ale] load issue
Christopher Fowler
cfowler at outpostsentinel.com
Thu Jun 22 07:27:57 EDT 2006
I had a problem like this on FC2 and ran into an interesting situation.
My load would be at 2+ and could rise but top showed nothing. I was
perplexed. Here the kernel said some processes were using up CPU and
top could not list those. The culprit was a few threads in tomcat.
Apparently we had some code written that did not understand that when
read() returns 0 it means the other end has terminated the connection.
Therefor Java IO was looping as fast as possible because it thought it
had something to read on a socket. read() would return 0 and it would
keep doing this. After a few of these threads the system would go to a
crawl. Strace was the _only_ way I found this. I killed a few
processes trying to see which one was a problem and then I attached to
java and saw what was going on. Restart tomecat and load went to 0.00.
It may be the way the FC2 kernel handled threads that confused top? I
do not know. The problem was that the JVM running tomcat was eating all
my CPU and top was useless in telling me this information.
On Thu, 2006-06-22 at 06:02, David Corbin wrote:
> On Thursday 22 June 2006 12:53 am, Benjie wrote:
> > do you have any zombie, or otherwise dead processes? I have seen my
> > load average go up mysteriously ( no real cpu load) when there was a
> > dead process that had a file locked.
>
> What's the best way to tell?
>
> David
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