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POAsyncTask will not stop running even after onPostExecute completes and blocks activity from being GC'd
 

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    <p>My activity does a lot of network I/O, so I start an AsyncTask (since you can not do network I/O on the UI thread) to accomplish this. My problem is that the when I call finish() to exit my application, the app is never garbage collected and continues to run in the background. I am assuming (perhaps incorrectly) that the task is never GC'd because the AsyncTasks are still running as the Eclipse debug window shows me. I have read everything I can find on this and it appears to be a problem without a solution.</p> <p>Here are the details:</p> <p>in OnCreate I create a MessageHandler as follows:</p> <pre><code>mMessageHandler = new Handler() { @Override public synchronized void handleMessage(Message msg) { switch( (int)msg.arg1) { case kMessageDoSomething: doSomething(); break; . . </code></pre> <p>I have a class for each AsyncTask, for example in myAsyncTask.java</p> <pre><code>public class myAsyncTask extends AsyncTask&lt;Void, Object, Object&gt; { @Override protected Object doInBackground(Void... params) { doSomeNetworkIO(); return null; } @Override protected void onPostExecute(Object result) { super.onPostExecute( result ); msg = new Message(); msg.arg1 = MyActivity.getInstance().kMessageDoSomething; MyActivity.getInstance().mMessageHandler.sendMessage( msg ); } </code></pre> <p>and back in myActivity</p> <pre><code>new myAsyncTask().execute(); </code></pre> <p>in the method doSomthing() I check the AsyncTask.Status of myAsyncTask and it is FINISHED, yet the debugger still shows the task as running and when I call finish() myActivity never terminates unless I use AppKiller to kill it manually.</p> <p>My real question here is, am I chasing a red herring? that is does the presence of running threads stop the activity from being garbage collected?</p>
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    1. COCan you clarify whether you're expecting the Application to get garbage collected per your first paragraph, or whether you're expecting your Activity to get GCd per your last? The Activity should be GCd unless something is holding a strong reference to it somewhere (which would be an error). You should not expect the Application to get GCd when you finish your activity. Sometimes it may, but usually it will not.
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    2. COcan you define what is a strong reference, for example my AsyncTask contains **MyActivity.getInstance()** does that constitute a strong reference? Does **final MyActivity activity = MyActivity.getInstance()** ?
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    3. COHi user330844. A strong reference is any normal java reference. The alternative to a strong reference is often a weak reference, which you can create using [java.lang.ref.WeakReference](http://download.oracle.com/javase/1,5.0/docs/api/java/lang/ref/WeakReference.html). There are other alternatives, such as soft or phantom references, but usually weak is what you're looking for on Android.
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