Eclipse won't quit with my plugin

Question

I'm developing my own Eclipse plugin and came across a very strange behavior. In some very specific cases, Eclipse won't quit when I close the workbench. It just stays hanging until I kill the process. This happens when running through PDE and when running as a regular installation.

It is really hard to provide more details and I know that it is a very generic question. Yet, I was wondering if anyone encountered such behavior and could share the solution.

Thanks. Zviki

PS. I'm attaching stack traces of all the running threads after the workbench is quit. Maybe something will pop out. This trace was achieved by running the IDE in debug mode, suspending it after it got frozen and copying all the threads tree.

Test1 [Eclipse Application] 
org.eclipse.equinox.launcher.Main at localhost:54840 (Suspended)    
    Daemon System Thread [Finalizer] (Suspended)    
        Object.wait(long) line: not available [native method]   
        ReferenceQueue<T>.remove(long) line: 120    
        ReferenceQueue<T>.remove() line: 136    
        Finalizer$FinalizerThread.run() line: 159   
    Daemon System Thread [Reference Handler] (Suspended)    
        Object.wait(long) line: not available [native method]   
        Reference$Lock(Object).wait() line: 474 
        Reference$ReferenceHandler.run() line: 116  
    Thread [main] (Suspended)   
    Daemon System Thread [Signal Dispatcher] (Suspended)    
    Daemon Thread [Thread-0] (Suspended)    
        OS.CFRunLoopRunInMode(int, double, boolean) line: not available [native method] 
        Display.sleep() line: 3902  
        IDEWorkbenchAdvisor(WorkbenchAdvisor).eventLoopIdle(Display) line: 364  
        Workbench.runEventLoop(Window$IExceptionHandler, Display) line: 2383    
        Workbench.runUI() line: 2346    
        Workbench.access$4(Workbench) line: 2198    
        Workbench$5.run() line: 493 
        Realm.runWithDefault(Realm, Runnable) line: 288 
        Workbench.createAndRunWorkbench(Display, WorkbenchAdvisor) line: 488    
        PlatformUI.createAndRunWorkbench(Display, WorkbenchAdvisor) line: 149   
        IDEApplication.start(IApplicationContext) line: 113 
        EclipseAppHandle.run(Object) line: 193  
        EclipseAppLauncher.runApplication(Object) line: 110 
        EclipseAppLauncher.start(Object) line: 79   
        EclipseStarter.run(Object) line: 386    
        EclipseStarter.run(String[], Runnable) line: 179    
        NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]  
        NativeMethodAccessorImpl.invoke(Object, Object[]) line: 39  
        DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 25  
        Method.invoke(Object, Object...) line: 585  
        Main.invokeFramework(String[], URL[]) line: 549 
        Main.basicRun(String[]) line: 504   
        Main.run(String[]) line: 1236   
        Main.main(String[]) line: 1212  
    Daemon Thread [State Data Manager] (Suspended)  
        Thread.sleep(long) line: not available [native method]  
        StateManager.run() line: 297    
        Thread.run() line: 613  
    Daemon Thread [Framework Event Dispatcher] (Suspended)  
        Object.wait(long) line: not available [native method]   
        EventManager$EventThread(Object).wait() line: 474   
        EventManager$EventThread.getNextEvent() line: 377   
        EventManager$EventThread.run() line: 317    
    Daemon Thread [Start Level Event Dispatcher] (Suspended)    
        Object.wait(long) line: not available [native method]   
        EventManager$EventThread(Object).wait() line: 474   
        EventManager$EventThread.getNextEvent() line: 377   
        EventManager$EventThread.run() line: 317    
    Thread [Worker-0] (Suspended)   
        Object.wait(long) line: not available [native method]   
        WorkerPool.sleep(long) line: 185    
        WorkerPool.startJob(Worker) line: 217   
        Worker.run() line: 51   
    Daemon Thread [Java indexing] (Suspended)   
        Object.wait(long) line: not available [native method]   
        IndexManager(Object).wait() line: 474   
        IndexManager(JobManager).run() line: 371    
        Thread.run() line: 613  
    Thread [Worker-1] (Suspended)   
        Object.wait(long) line: not available [native method]   
        WorkerPool.sleep(long) line: 185    
        WorkerPool.startJob(Worker) line: 217   
        Worker.run() line: 51   
    Thread [Worker-2] (Suspended)   
        Object.wait(long) line: not available [native method]   
        WorkerPool.sleep(long) line: 185    
        WorkerPool.startJob(Worker) line: 217   
        Worker.run() line: 51   

Answer 1

Sorry to bother everybody... got the problem.

My problem was simple: one of my Action Handlers threw an exception in the Dispose method. This causes the entire workspace to hang.