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

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.

Here are the details:

in OnCreate I create a MessageHandler as follows:

mMessageHandler = new Handler()
{
@Override
public synchronized void handleMessage(Message msg)
{
  switch( (int)msg.arg1)
  {
         case kMessageDoSomething:
           doSomething();
           break;
                          .
                          .

I have a class for each AsyncTask, for example in myAsyncTask.java

public class myAsyncTask extends AsyncTask<Void, Object, Object>
{
    @Override
protected Object doInBackground(Void... params)
{
         doSomeNetworkIO();
         return null;
    }

@Override
protected void onPostExecute(Object result)
{
    super.onPostExecute( result );
    m开发者_Python百科sg = new Message();
    msg.arg1 = MyActivity.getInstance().kMessageDoSomething;
    MyActivity.getInstance().mMessageHandler.sendMessage( msg );
    }

and back in myActivity

new myAsyncTask().execute();

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.

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?

The AsyncTask has a thread pool, so even if your work is finished threads are not terminated, that is probably what you are seeing in the debugger. The pool is shut down by finalize(), so it doesn't shut down until the object is GC-ed. What you might want to do is make sure your AsyncTask doesn't hold a reference to the activity and vice versa. You can detach them onDestroy().

Keep in mind that regardless of GC, if Android is low on memory, it will just terminate the process of your unused activity, so memory will be eventually reclaimed.