On Fri, 2005-03-18 at 18:48 -0800, Chris Hyzer wrote:
currently looking
into memory-leak issues with j2ee/servlet-engine
We have about a dozen apps on 2 tomcats that have
800MB each in linux (5.0.25), and they are not huge
apps, but after a few manager reloads the tomcat is
out of memory. Is this related? You said undeploy,
but maybe reloading is also a problem. Also, if we
let the server run for a while, we cannot add new apps
either. I suspect we need to profile and look for
memory leaks, but I thought it would mention it. Chris
It might be the same problem. By undeploy I mean throw away the
classloader associated with the deployed component, which reload will
also do.
The problem is that both commons-logging and commons-beanutils use the
Singleton pattern. And the Singleton pattern is *extremely* hard
(possibly impossible) to implement correctly in a j2ee-style environment
when a class might be loaded via a shared classloader.
Tomcat includes a workaround for commons-logging which appears *to me*
to be a complete fix for commons-logging leaks (though maybe not a very
elegant one): it calls
org.apache.commons.logging.LogFactory.release(this)
from class WebappClassLoader. However there have been reports of leaks
when using commons-logging despite this; I need to try to set up some
testcases to determine what's going on, but testcases involving
garbage-collection and complex classloading setups will be tricky to
create.
If you do find anything from profiling your app, please post the info to
this group (and/or me).
Note that I'm going to be away for the next three weeks, but will try to
pick this topic up when I return.
Cheers,
Simon
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