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From Peter Crowther <peter.crowt...@melandra.com>
Subject Re: Tomcat Thread utilization growing very large causing a hung tomcat instance
Date Tue, 03 Aug 2010 15:04:20 GMT
What happens if you *reduce* the allocated heap size - do you actually need
that much Java heap?  Native threads are created outside of the Java heap.
You have 2G for (4 * 400) = 1600 threads plus the OS, or about 1 Mbyte per
thread (this assumes no swap space).  That may not be enough.

- Peter

On 3 August 2010 15:21, Tomcat Novice <tomcat.novice@gmail.com> wrote:

> Hi,
>
> I hope someone can help me. I am new to tomcat and I have been encountering
> issues where a particular tomcat instance/s are having large thread count
> during load testing and results in a hung state. The error shown on the
> browser is: java.lang.OutOfMemoryError: unable to create new native thread
> (stack trace attached)
>
> Environment:
>
> OS: Windows 2003 64 bit
> JDK 1.5
> 8GB Total Machine RAM
> 4 Tomcat 5.5 instances running as a service on one Physical Server (each
> Tomcat configured to use 1.5GB of Heap) 4 instances x 1.5GB = 6GB of Heap
> 4 Identical servers configured the same way and load balanced
> IIS Web Server front end (AJP Port configured) no maxThreads property is
> set on server.xml for AJP port declaration. Per documentation (
> http://tomcat.apache.org/tomcat-5.5-doc/config/ajp.html), if no value is
> set maxThreads are set to 200
>
> Not all 4 servers are experiencing this problem.
>
> 1. Any ideas how I can resolve/isolate this problem?
> 2. I know I need to do a thread dump but I am not familiar on how to
> analyze thread dumps from Tomcat. Can you point me to documententation on
> how I can analyze thread dumps from Tomcat?
> 3. Also, can someone confirm if the thread dumps from JDK 1.5 are the same
> as the Thread Dumps from a JDK 1.6? I seem to be getting different formats.
> Can someone just confirm?
> 4. If the maxThread is set to 200, why are the Tomcat instances utilizing
> up to 400 Threads (see screenshot)
>
> Regards,
>
> Tomcat Novice
>
>
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