Is there any way to prevent Grails permgen leaking on redeploy in production mode on tomcat despite JVM flags

Question

It's a familiar old problem but I really want to put it to bed once and for all! I've got the following JVM flags set:

-XX:+CMSClassUnloadingEnabled 
-XX:+CMSPermGenSweepingEnabled -Dorg.apache.catalina.loader.WebappClassLoader.ENABLE_CLEAR_REFERENCES=true

but I still observe the permgen usage notch up by a good 50MBs for every deployment cycle. I'm deploying remotely using the Tomcat manager application, and Grails is in production mode.

If it gets too full then a kill -9 is necessary!

I might try using JRockit but nor now it's not an option. I don't really find it acceptable in a production environment to have to bounce the whole container every once in a while.

Oliver Tynes · Accepted Answer · 2011-11-25T20:07:38.520

2

Permgen leakage is an issue no matter what appserver you're on when using grails is my experience (highly personal and probably easily contendable anecdote, just to be clear on that ;) ).

If this is the only app you have deployed, why not just shutdown.sh, delete webapp folder, put in war and then startup.sh ?

It's the way we go and the redeployment only gains about 7 seconds (where 5 of those are a sleep 5 to ensure catalina is fully shutdown before it goes back up).

Edit:

Having one tomcat instance per app is pretty cool anyways in my opinion!

edited Nov 25 '11 at 20:07

answered Nov 25 '11 at 19:59

Oliver Tynes

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I would replace 'grails' with 'tomcat' :) – prusswan Nov 25 '11 at 20:01
Well, even with 2gb permgen handed out to glassfish we would run out of permgen space eventually. Also, having 'tomcat' on a appserver is non-sensical ;) – Oliver Tynes Nov 25 '11 at 20:07
glassfish is an even worse offender imho :) – prusswan Nov 25 '11 at 20:08
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Sounds like the question should be, what app server doesn't leak permgen, ever! – barrymac Nov 28 '11 at 11:06
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Would not be able to write an answer then :P – Oliver Tynes Nov 28 '11 at 17:03

score 1 · Answer 2 · answered Nov 25 '11 at 20:03

You may not be aware of this, but permgem will occur eventually as long as you repeatedly hot deploy to the Tomcat instance, since there are some classes that can never be properly unloaded (either due to the way the classes are programmed, or some limitation on the part of Tomcat) no matter which parameters you use, short of a restart.

Is there any way to prevent Grails permgen leaking on redeploy in production mode on tomcat despite JVM flags

2 Answers2