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From "Caldarale, Charles R" <Chuck.Caldar...@unisys.com>
Subject RE: Tomcat 5.5.20 Stops Responding
Date Thu, 27 Sep 2007 02:14:42 GMT
> From: Etienne Lacombe [mailto:etiennel@scientology.net] 
> Subject: Tomcat 5.5.20 Stops Responding
> 
> I followed your advice and killed the JVM so as to get the 
> stack trace when it stopped responding this afternoon.

It's not actually necessary to terminate the process in order to trigger
a thread dump.

> 3:27 org.apache....ThreadPool logFull
> All threads (250) are currently busy, waiting. Increase 
> maxThreads (250) or check the servlet status.

Do you really expect to have 250 active connections?  Or are the threads
stuck waiting on something to unlock?  If you have keep-alives enabled
and 250 active clients, and are not using the APR connector, then there
will be a Tomcat thread dedicated to each active connection.

> 3:41 - the stack trace dump... All threads are either 
> TIMED_WAITING, RUNNABLE or WAITING.

That's pretty much all the states you're going to see.  The real
question is what are the threads in the WAITING state waiting for?
Check the objects they're waiting on, and see if you have a deadlock
situation in your webapp, or perhaps an unresponsive external resource
(e.g., data base server).  Yet another possibility is that you're not
closing data base connections properly, resulting in none being
available for new requests.  Missing try/finally clauses around data
base requests is the usual culprit in the last case.

 - Chuck


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