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From Zoran Avtarovski <zo...@sparecreative.com>
Subject Re: Help in diagnosing server unresponsiveness
Date Fri, 01 Feb 2013 03:32:05 GMT
Howard, Igor,

Thanks for your responses. In relation to more detail:

1.The app has been running on Tomcat 7 in a virtualised linux environment
for about 4 months and the issue has been persistent through that time.
Prior to that it was running on a physical Windows server with no issues.
The move to linux coincided with the addition of a substantial amount of
WebServices functionality - consuming.
2.The tomcat instance was originally running with a max of 6Gb of
allocated memory and it would crash almost daily. When we upped it to 11gb
the crashes reduced to about twice a week.
3. Tomcat is configured with the following options export
JAVA_OPTS="-Xms256m -Xmx11460m -Djava.awt.headless=true
-XX:MaxPermSize=256M -XX:+CMSClassUnloadingEnabled
-XX:+UseConcMarkSweepGC"
4. Xms and MaxPermSize were just reduced from 512m
5. The app generally has about 50-100 concurrent users - the logs show
that Tomcat can crash with as few as 20 users. I'm wondering if it could
be GC related as the crashes often follow periods of heavy use.
6. The app is a struts2 based app using Spring 3.5 for dependancy
injection/ioc.

The problem with getting a thread dump is that high CPU usage is only a
spike and server freezes. CPU usage only goes above 5-10% when it's about
to crash. Support then reboot the server instances and off it goes. I've
tried to spend a few days just watching, but of course it didn't skip a
beat while I was monitoring. Is there a way to trigger gather relevant
data when Tomcat crashes?

Z.



On 1/02/13 12:36 PM, "Zoran Avtarovski" <zoran@sparecreative.com> wrote:

>Hi Guys,
>
>We have a application running on the latest Tomcat7 and we are getting a
>server crash or becoming unresponsive. This occur every few days at no
>fixed
>intervals or time of day and they certainly don't correlate to any app
>function ­ at least not according to the logs.
>
>We set setup monitoring using JavaMelody and what we see is dramatic
>spikes
>in CPU and memory usage at the time of the crash.
>
>Memory hovers around 3-5% for the rest of the time and CPU is the same.
>
>I've looked at the number of sessions, HTTP activity , jdbc activity and
>nothing obvious jumps out.
>
>I'd really appreciate your collective wisdom in putting into practice some
>strategies to identify the cause of the spikes. This driving me and my
>team
>nuts.
>
>Any help would be appreciated.
>
>Z.
>
>



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