Callable and future delay android main thread

Question

I want to fetch some data from service by callable and future. This is one of my code:

@Override
public void getCIFilesType(Consumer<String> consumer) {
    try {
        consumer.accept(serviceExecutor.submit(() ->
                service.getCi(EsupFactory.getConfigString(SETTING_ROOT_CI) + "GetCI",
                        translator.makeCiJsonObject("PCiName", "CI_FilesType")).execute())
                .get().body().string());
    } catch (ExecutionException | InterruptedException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

I have 10 method like this that execute like above.I used Executor service to run callable :

ExecutorService serviceExecutor = Executors.newSingleThreadExecutor();

I'm my activity I have a menu and then click on one item in the menu a fragment is a transaction in activity. All of the thread tasks immediately started in onViewCreated in fragment:

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    presenter.getCis();
}

But when I clicked on the menu item UI is frizzed till all task down then transaction is down. This is not the first time that I have this problem. Every time I use callable and executor service I do not know why UI is frizzed!!!!

This is profiler :

Someone has some guidance for me!!? Please do not tell me to use asyncTask :-)

What is a read line?? In ui thread I just do transaction not execute long running task!!!

score 1 · Accepted Answer · answered Feb 19 '19 at 11:29

1

It happens because you're calling get() on the future returned by execute() method. According, to the docs,

If you would like to immediately block waiting for a task, you can use constructions of the form result = exec.submit(aCallable).get();

So, even though you use a background thread, by calling get you block your main thread until the background thread finishes your task.

To avoid UI junks you should've used callbacks.

answered Feb 19 '19 at 11:29

Stanislav Shamilov

1,746
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20

What does mean `used callbacks`? I used `Consumer` as a callback!! I did not understand what is your point of `used callbacks` ?@StanislavShamilov – Cyrus the Great Feb 19 '19 at 11:52
Yes, you used it as a callback, but the problem is that you're calling get method. As I mentioned before, it's a blocking method, so calling thread(in this case, it's a Android Main Thread), will be blocked until a background thread finishes it's task. So call of the Consumer's accept method will be delayed until this get method is executed. – Stanislav Shamilov Feb 19 '19 at 12:10
I think, this SO post can help you: https://stackoverflow.com/questions/826212/java-executors-how-to-be-notified-without-blocking-when-a-task-completes. Or you can try using some frameworks to deal with concurrency, for example, RxJava – Stanislav Shamilov Feb 19 '19 at 12:11

Callable and future delay android main thread

1 Answers1