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From "Arnab Chakravarty" <>
Subject RE: Threads issues in Tomcat 5.0.28
Date Wed, 08 Dec 2004 03:49:57 GMT

I see your problem similar to mine some time in the past. What you need
to is the following:

- Lower the number of threads and keep it close to 120-150 threads.
- Are you using a database, if yes, check if the DB connection pool is
the bottleneck
- Yes, you can find what the 200 threads are doing by taking a
threaddump. The way to do this is to use the command - kill -QUIT
<tomcat pid>.

Hope this helps.


-----Original Message-----
From: Matt Robinson [] 
Sent: Wednesday, December 08, 2004 8:02 AM
Subject: Threads issues in Tomcat 5.0.28


We have 5 instances of Tomcat 5.0.28 running on their
own high performance servers (dual XEON / 2GB RAM,
etc) receiving AJP13 connector requests via our main
web server which has IIS 5, IIS redirector, and

This works great even under high loads except for one
thing: after several hours of usage (could be 3 hours
or up 24 hours), the number of Tomcat threads on the
5.0.28 systems will suddenly increase at a rapid rate
until Tomcat no longer responds to requests. It will
hit the max # threads (which defaults to 200) and
essentially freeze until it is restarted.

This is strange because this behavior does not seem to
correspond to increased usage of the particular server
it occurs on. We are not sure what is triggering this
and what those Tomcat threads are waiting on [they
remain busy, waiting and unable to be reused by

My questions are:
1. Has anyone else experienced this kind of Thread
explosion problem?
2. Is there a way to find out exactly what each Tomcat
Thread is doing/waiting for?
3. Is there a way to periodically clear Tomcat's
threadpool -- i.e. get rid of waiting/busy/unusued

We are working on ways to automatically restart Tomcat
once a certain # of threads is reached, but this is
not an acceptable solution, only a temporary
workaround of course.

Many thanks in advance

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