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From "Mark Stevens" <mark.steven...@googlemail.com>
Subject Re: Tomcat consuming entire CPU.
Date Tue, 24 Jul 2007 16:41:46 GMT
Hi, and thanks for responses,

I don't think we are using sendfile, to be honest, I've had no
involvement in development of the code, I'm just requested to look
after the server.

I'm going to try and work out how to read thread dumps, hopefully this
will help, I'm finding my X11 connection too slow for J-Profiler to be
usable.

I apologise for not being to Savvy with my environment versions I get
a bit confused with all the different Java environments like
JDK/JRE/SDK/J2SE/J2EE etc....

The version of java executed by Tomcat that consumes CPU is ....

  /usr/java/bin/java -version
java version "1.3.1_14"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1_14-b03)
Java HotSpot(TM) Client VM (build 1.3.1_14-b03, mixed mode)

Tomcat is version 4.1

I'll see if moving version's to 1.3.1_20 changes things.


I can reproduce similar behavior to live environment on dev consuming
an entire CPU by running Apache Benchmark to simulate 20 concurrent
sessions requesting the homepage 10000 times.....

./ab -c20 -n 10000 http://<url><tomcat port>/


Something else I noticed in my Live envrionment is that Oracle is
hogging all the memory and tomcat is being forced into swap.

I'll crack on with investigations and post to group if I find anything
worth sharing.

Many thanks again,

Mark.










On 24/07/07, Caldarale, Charles R <Chuck.Caldarale@unisys.com> wrote:
> > From: Mark Stevens [mailto:mark.stevens99@googlemail.com]
> > Subject: Tomcat consuming entire CPU.
> >
> > My JRE:java version "1.3.1_14"
>
> You might want to try a JRE that is a bit more up to date than that.
> The 1.3.1 leg is up to _20 and even that is unsupported on everything
> other than Solaris 8 (falls into the "Vintage Support Period").  Do you
> have the required Solaris patches installed?  Also, shouldn't that be a
> JDK, not a JRE?
>
> > The server is running Oracle, Tomcat, Apache 2.2 and a Content
> > Management System, Operating system is Solaris 8 running on sun4u Sun
> > Fire V240 with 4GB of RAM.
>
> What Tomcat version?  Current ones require a 1.4 or 1.5 JRE.
>
> > Every so often the java process for Tomcat consumes an entire CPU, and
> > requires Tomcat to be killed, and then restarted, this is happened
> > quiet load with only a couple of HTTP requests coming through every
> > second.
>
> What does a thread dump show?
>
> > I've heard it's not good to set Xms too high.
>
> You can't set it larger than whatever the maximum contiguous virtual
> space for a process is, but that's the only consideration.  Regardless,
> that's unlikely to be your problem.
>
>  - Chuck
>
>
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