Re: Tomcat NT Service hogs >90% CPU - intermittent problem

[Ben Walding]

I didn't notice the java processes thrashing. When I checked task manager it was just the tomcat.exe that was at high cpu usage.
I also don't know where the tomcat.exe comes from, presumably someone builds it at the same time they build the install wizard etc.

You could try -Xloggc:<file>
(from JDK1.4.1 - no idea if it exists on anything earlier)


Christopher Watson wrote:

Many thanks Ben

I've similarly NOT YET seen the >90% CPU on a
jdk1.4 and tomcat 4.1.12 system I set up
with much the same webapps as the one that's "thrashing"

I noticed some old mailing list messages related to this problem that talked
about garbage collection,
and I had begun to wonder whether >90% CPU was a jdk problem rather than a
tomcat problem
and your experience supports this.

Do you - or anyone else - know the pedigree of tomcat.exe?
Is it basically JavaService?

Also, has anyone any ideas how I might get -verbose:gc output from it?
I can do this with catalina_opts for catalina.bat,
but adding the -verbose:gc parameter to the registry key for the NT service
doesn't seem to result in any output for -verbose:gc,
though the -Xms64m and -Xrs parameters I've added do seem to be actioned.

Thanks again Ben

-----Original Message-----
From: Ben Walding [mailto:ben@;walding.com]
Sent: 06 November 2002 07:14
To: Tomcat Users List
Subject: Re: Tomcat NT Service hogs >90% CPU - intermittent problem


I had this problem at one point (4.1.10, and no IIS in my config though)

My "solution" was to upgrade to 4.1.12 and upgrade the JDK to 1.4.1.01,
this seemed to work.

No idea what caused it though.


Christopher Watson wrote:

Hello All,

Currently my config is

TOMCAT 4.1.12
jdk1.3.1_03
Windows 2000 Pro
NT Service configured using the server\jvm.dll with -Xrs
IIS 5.0
ISAPI_REDIRECTOR version 2.0 using workers.properties

however I have had this problem many times with different tomcat

versions in

the past.

Suddenly, for no apparent reason - high load/ no load/ different webapps/
doesn't seem to make any difference ...
tomcat.exe grabs >90% of cpu and won't let go of it.
Nothing unexpected appears in the logs

Has anyone seen this and know a way round it?

Failing that, could they suggest any logging I could turn on (and how) to
try and diagnose the problem.

As I say, I've had it with various combinations of applications

in webapps.

I THINK it ONLY happens with the NT Service tomcat.exe,
I'm pretty sure I've not seen it by running catalina.bat

Sometimes it happens if I restart the machine and leave it.
Other times I may not encounter it for a couple of days.
If I leave about a week, then it almost always turns up.

Any help much appreciated .

Christopher


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