Re: PermGen OutOfMemory, JRuby 1.2.0

 From the GlassFish end of things, we've noticed three things that cause
this.

The first is Grizzly caching Request objects in thread local. While
that's good for performance reasons, it ends up meaning that a reference
to the JRuby runtime will stick around until the cache is cleared. There
should be a fix in the next released version of GlassFish (both gem and
server), and in the mean time you can "manually" clear the cache by
sending several requests to the server after undeploy, such as to a
non-existent contextroot.

We've also seen some issues around JRuby unregistering itself as a
secure communications provider (through JRuby-openssl). Similarly, that
ends up keeping a reference to a JRuby runtime, so that things aren't
collected. I know that the JRuby people are working on getting a fix
together for that, in the mean time the default JRuby limited openssl
doesn't seem to have this issue.

Lastly, there is
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4957990 , which
likely affects all of the listed application servers. As mentioned in
the bug, increasing permgen size (while having class unloading enabled)
will cause correct behavior and no leak. I'm working with one of the JDK
team members to get a fix for this finally integrated into the JDK.

Tomcat and JBoss may have other, or additional, causes of permgen
leakage. I haven't looked into this using them, so I can't provide much
information there.

Chad Johnson wrote:

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