AsyncTask is using the same thread and queueing all my requests

Issue

In my Android app, I figured out that all my api calls are being queued instead of happening concurrently. I'm assuming they are all being posted to the same thread, while I was under the impression that an AsyncTask creates a new thread for doInBackground().

public class API extends AsyncTask<String, String, String> {
    public interface Listener {
        void completedWithResult(JSONObject result);
    }
    public Listener listener;
    @Override
    protected String doInBackground(String... strings) {
        if(!canMakeRequest()){
            return internetError().toString();
        }
        String action = strings[0];

        Log.i("API", action +" Sent");
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        Log.i("API", action +" Received");
        return "";
    }

    @Override
    protected void onPostExecute(String json) {
        JSONObject obj;
        obj = new JSONObject(json);
        if(listener != null)listener.completedWithResult(obj);
    }
}

In a whole bunch of places in my app I have things like:

API api = new API();
api.listener = new API.Listener() {
    @Override
    public void completedWithResult(JSONObject result) {
        Log.i(tag, "Returned with "+result);
    }
};
api.execute("update-address/");

And I always create a new instance of API, but my logs have all of these calls happening serially and not in parrallel:

analytics/log/ Sent
analytics/log/ Returned
get-beta-tester Sent
get-beta-tester Returned
get-following Sent
get-following Returned
get-groups Sent
get-groups Returned
get-follow-requests Sent
get-follow-requests Returned
get-followers Sent
get-followers Returned
analytics/log/ Sent
analytics/log/ Returned
analytics/log/ Sent
analytics/log/ Returned
post-session Sent
post-session Returned
analytics/log/ Sent
analytics/log/ Returned
post-session Sent
post-session Returned
analytics/log/ Sent
analytics/log/ Returned
analytics/log/ Sent
analytics/log/ Returned
unregister-GCM Sent
unregister-GCM Returned
analytics/log/ Sent
analytics/log/ Returned
verify Sent
verify Returned

Solution

See here:

https://developer.android.com/reference/android/os/AsyncTask.html

When first introduced, AsyncTasks were executed serially on a single background thread. Starting with DONUT, this was changed to a pool of threads allowing multiple tasks to operate in parallel. Starting with HONEYCOMB, tasks are executed on a single thread to avoid common application errors caused by parallel execution.

and the solution is to:

If you truly want parallel execution, you can invoke executeOnExecutor(java.util.concurrent.Executor, Object[]) with THREAD_POOL_EXECUTOR.

api.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, "update-address/");

Answered By - marcinj