Cannot run more than two asynctask concurrently

Question

When I run multiple AsyncTasks in my view using AsyncTask.THREAD_POOL_EXECUTOR flag I found that no more than two AsyncTasks running concurrently. Actually when two AsyncTasks complete their work next two get started. I also try this AsyncTask test project in github. I got a same result, looking at logcat there where no more two AsyncTasks running concurrently.

How can I run more than two asynctasks concurrently?

http://stackoverflow.com/questions/9593850/is-there-a-limit-of-asynctasks-to-be-executed-at-the-same-time — Pavlos, Sep 26 '14 at 19:09
@Pavlos The link says: AsyncTask is backed by a ThreadPoolExecutor with a core pool size of 5, but a maximum pool size of 128 (from 1.6 - 4.0.3). I got confused why I can't have 4 AsyncTasks at the same time! — Misagh Emamverdi, Sep 26 '14 at 19:21
@blackbelt Yeah, the problem is solved. Executor is the solution. Thanks :-) — Misagh Emamverdi, Sep 26 '14 at 19:44

score 2 · Answer 1 · answered Sep 26 '14 at 19:26

The documentation 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 that means that they are executed on a single thread, meaning, by default, you can only have one AsyncTask active at a time.

But, fear not, the documentation further states:

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

So... new MyTask().executeOnExecutor( AsyncTask.THREAD_POOL_EXECUTOR );

will do the trick for you.

Cannot run more than two asynctask concurrently

1 Answers1