Is it necessary to cancel Async Task?

Question

So I have been handed an Android Application, I noticed that in the Fragment's onStop lifecycle method they did the following:

    if(mWorkerTask!=null)
    {       
        AsyncTask.Status taskStatus=mWorkerTask.getStatus();

        if(taskStatus==Status.RUNNING||taskStatus==Status.PENDING)
        {
            mWorkerTask.cancel(true);
        }
    }

I still don't understand why they did this, is it a requirement to cancel an AsyncTask in the onStop method?

Answer 1

Not necessarily butit is a good practice to stop using any resources allocated to your app while it was in foreground or doing some useful stuff for the user for example downloading/uploading some data from internet, after it's purpose is finished.

It is the same as closing a file or database when it is no longer required. Even if you remove the above code from onStop(), it won't affect your app ( if it is not used by some other process) but canceling asynctask will save memory and cpu cycles eventually battery.

Hope this helps.