Re: Tomcat/Struts app hanging (Waiting for xx instance(s) to
be deallocated) 2003-10-07 - By Justin Ruthenbeck
Back
At 04:23 PM 10/7/2003, you wrote:
>>Can you collect the output from sending Tomcat the -QUIT signal when this
>>happens?
>
>I am not sure I understand this one.
>
>I am kinda restricted on the deployment machine (the linux machine
>mentioned above) - it was developed on a Solaris 9 machine and moved over
>- everything works pretty normal 'cept this freezing problem. Same
>versions of all software on both machines tho (java,mysql,tomcat,struts).
>
>I can ask the admin to give me the output of it the next time it freezes
>(we are periodically restarting it right now via cron just to make sure
>there is as little downtime as possible).
Basically, you've got XX number of non-daemon threads that are busy doing
*something* such that the process can't shutdown. These threads might be
something your application has created (easier), or something created by
Tomcat (I've seen this happen on several machines running Tomcat with AJP13
Connector) which is much more difficult.
To debug it, you need a Thread dump of all threads in your app. Next time
your app freezes, give it a kill -3 <pid> to get the thread dump to
StdOut. From there, you should see XX threads spining wheels
somewhere. If they're not spinning, it's also possible that you have
deadlocked threads. This could explain why subsequent requests fail,
especially if the dealock is happening on some static resource.
Hope that helps ... am curious to hear what you find out. Please keep me
posted.
justin
__ ____ ____ ____ ____ ____ ____ ___
Justin Ruthenbeck
Software Engineer, NextEngine Inc.
justinr - AT - nextengine DOT com
Confidential
See http://www.nextengine.com/confidentiality.php
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