[WW-2167] Memory leak when app stopped

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.9
• Fix Version/s: 2.1.8.1

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

• Assignee: Unassigned
• Reporter: Adam Crume
• Created: 10/Sep/07 19:13
• Updated: 06/Jan/10 08:48
• Resolved: 06/Jan/10 08:48

Description

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.