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From "Sean Kleinjung (JIRA)" <j...@apache.org>
Subject [jira] Commented: (WW-2167) Memory leak when app stopped
Date Thu, 07 Feb 2008 21:44:39 GMT

    [ https://issues.apache.org/struts/browse/WW-2167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=43164#action_43164
] 

Sean Kleinjung commented on WW-2167:
------------------------------------

There is a memory leak in XWork 2.0.4 documented as Jira issue XW-560 (http://jira.opensymphony.com/browse/XW-560).
This issue is fixed in XWork 2.1.0. However, several classes that Struts uses were removed
in this version, so it is not possible to deploy Struts 2.0.11 with XWork 2.1.0. I have fixed
this issue temporarily by patching my XWork 2.0.4 jar with the fix for this bug.

In order to fix this leak in Struts, a future version will need to be released that uses XWork
2.1.0 or later.

> Memory leak when app stopped
> ----------------------------
>
>                 Key: WW-2167
>                 URL: https://issues.apache.org/struts/browse/WW-2167
>             Project: Struts 2
>          Issue Type: Bug
>    Affects Versions: 2.0.9
>         Environment: WebSphere 6.1.0.9 (non-network deploy) on Windows XP Professional
> java version "1.5.0"
> Java(TM) 2 Runtime Environment, Standard Edition (build pwi32devifx-20070608 (SR5+IY99712))
> IBM J9 VM (build 2.3, J2RE 1.5.0 IBM J9 2.3 Windows XP x86-32 j9vmwi3223-20070426 (JIT
enabled)
> J9VM - 20070420_12448_lHdSMR
> JIT  - 20070419_1806_r8
> GC   - 200704_19)
> JCL  - 20070608
>            Reporter: Adam Crume
>             Fix For: 2.1.2
>
>         Attachments: log_leak.png
>
>
> Struts 2 somehow prevents the app's classes from being garbage collected when the application
is stopped or undeployed.
> I created a barebones Struts 2 app with an action with the following code:
> 	private static final Object x = new Object() {
> 		{
> 			System.out.println("================== Object created: " + hashCode() + " ===================");
> 		}
> 		protected void finalize() throws Throwable {
> 			System.out.println("**************** Object finalized: " + hashCode() + " *********************");
> 		};
> 	};
> Because of this static field, a message should be printed when the class is initialized
and when it is garbage collected.  "Object created" would be printed out whenever I went to
the action for the first time, but restarting the app never printed "Object finalized."  This
is not an issue with garbage collection in my web container because doing the same thing with
a servlet resulted in both messages being printed.
> One problem is that the FilterDispatcher.init() method sets a ThreadLocal but never clears
it.  I fixed that by adding ActionContext.setContext(null); to the end of the init() method,
but that didn't solve the larger problem.

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