CODEWITHSUNDEEP
springhibernatetomcatmemory
Santosh
Santosh

Reputation: 83

Tomcat - PermGen space Exception

Iam using Tomcat 6, springs, hibernate and struts in my application. Often i get this exception in logs regarding memory and the site hangs and stops responding. Iam not sure whats wrong. Can anybody suggest what changes has to be done to avoid this.

org.apache.tomcat.util.threads.ThreadPool$ControlRunnable run SEVERE: Caught exception (java.lang.OutOfMemoryError: PermGen space) executing org.apache.jk.common.ChannelSocket$SocketConnection@2c52d3, terminating thread

Upvotes: 0

Views: 1776

Answers (2)

Jyoti Dutta
Jyoti Dutta

Reputation: 68

The PermGen space is what Tomcat uses to store class definitions (definitions only, no instantiations) and string pools that have been interned. From experience, the PermGen space issues tend to happen frequently in dev environments really since Tomcat has to load new classes every time it deploys a WAR or does a jspc (when you edit a jsp file). Personally, I tend to deploy and redeploy wars a lot when I’m in dev testing so I know I’m bound to run out sooner or later (primarily because Java’s GC cycles are still kinda crap so if you redeploy your wars quickly and frequently enough, the space fills up faster than they can manage).

This should theoretically be less of an issue in production environments since you (hopefully) don’t change the codebase on a 10 minute basis. If it still occurs, that just means your codebase (and corresponding library dependencies) are too large for the default memory allocation and you’ll just need to mess around with stack and heap allocation. I think the standards are stuff like:

-XX:MaxPermSize=SIZE I’ve found however the best way to take care of that for good is to allow classes to be unloaded so your PermGen never runs out:

-XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled Stuff like that worked magic for me in the past. One thing tho, there’s a significant performance tradeoff in using those, since permgen sweeps will make like an extra 2 requests for every request you make or something along those lines. You’ll need to balance your use with the tradeoffs.

Upvotes: 2

HariKrishnan
HariKrishnan

Reputation: 356

Your application may either have a memory leak or your Tomcat may not have enough memory to run the application. Use tools like Yourkit to check your memory usage.

Edit: Try increasing Tomocat memory. By default it starts with 256 MB. If you are on Windows you can do this by configuring Tomcat process settings. Refer to below post. How do I increase memory on Tomcat 7 when running as a Windows Service?

Upvotes: 0

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