Best practice: AsyncTask during orientation change

Do NOT use android:configChanges to address this issue. This is very bad practice.

Do NOT use Activity#onRetainNonConfigurationInstance() either. This is less modular and not well-suited for Fragment-based applications.

You can read my article describing how to handle configuration changes using retained Fragments. It solves the problem of retaining an AsyncTask across a rotation change nicely. You basically need to host your AsyncTask inside a Fragment, call setRetainInstance(true) on the Fragment, and report the AsyncTask's progress/results back to it's Activity through the retained Fragment.

I usually solve this by having my AsyncTasks fire broadcast Intents in the .onPostExecute() callback, so they don't modify the Activity that started them directly. The Activities listen to these broadcasts with dynamic BroadcastReceivers and act accordingly.

This way the AsyncTasks don't have to care about the specific Activity instance that handles their result. They just "shout" when they're finished, and if an Activity is around that time (is active and focused / is in it's resumed state) which is interested in the results of the task, then it will be handled.

This involves a bit more overhead, since the runtime needs to handle the broadcast, but I usually don't mind. I think using the LocalBroadcastManager instead of the default system wide one speeds things up a bit.