How can I run tasks in parallel within an AsyncTask?

Question

I have three tasks running within an AsyncTask class. I want to run these tasks in parallel, without making use of three AsyncTask classes. Is this possible? If yes, how could it be done?. Below you can find a code snippet of my AsyncTask class and its doInBackground method.

private class AsyncBenchmarking extends AsyncTask<Void, Void, Integer> {
    @Override
    protected void onPreExecute() {
        lockScreenOrientation();
        animateScreen();

        super.onPreExecute();
    }

    @Override
    protected Integer doInBackground(Void... params) {

        firstTaskPerformance = objPrimeNumber.generatePrimeNumbers();
        secondTaskPerformance = objLinpack.linpackBenchmark();
        thirdTaskPerformance = objSuperPi.calculatePi(100000);

        return;
    }
}

Get rid of the `AsyncTask` and use three `Threads`, if you do not want to use `AsyncTask`. — CommonsWare, Oct 26 '16 at 18:04
Use `ExecutorService` and run your tasks (`Runnable`s) on it. It's the best option. — Beloo, Oct 26 '16 at 18:16

score 3 · Answer 1 · answered Oct 26 '16 at 18:14

The api says :

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.

So, for parallel execution :

@TargetApi(Build.VERSION_CODES.HONEYCOMB) // API 11
void startMyTask(AsyncTask asyncTask) {
    if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
        asyncTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, params);
    else
        asyncTask.execute(params);
}

Hope it helps !

Vyacheslav · Answer 2 · 2016-10-26T18:29:15.213

2

You can use Thread instead.

new Thread((new Runnable() {

        @Override
        public void run() {
            //somecode 1
        }
    }).start();
new Thread(((new Runnable() {

        @Override
        public void run() {
            //somecode 2
        }
    }).start();
new Thread(((new Runnable() {

        @Override
        public void run() {
            //somecode 3
        }
    }).start();

edited Oct 26 '16 at 18:29

answered Oct 26 '16 at 18:05

Vyacheslav

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those asynctasks will run serially. – njzk2 Oct 26 '16 at 18:12
@njzk2 , I rare use `asynctask` class because of a lot of those disadvantages. – Vyacheslav Oct 26 '16 at 18:33

score 0 · Answer 3 · answered Oct 26 '16 at 18:09

Thread should not be manipulated directly. You should use instead ExecutorService class like describe here : https://developer.android.com/reference/java/util/concurrent/ExecutorService.html

If you want to execute three tasks in parallel then set poolSize to 3

Nothing more, nothing less

How can I run tasks in parallel within an AsyncTask?

3 Answers3