@Async with outstream and thread.sleep method

Question

A simple question on @Async annotation.

For example: A method is @Async annotated and it contains thread.sleep for few seconds. And after the sleep, their is a outStream.println. Then what is the result.

I have used ThreadPoolTaskExecutor as executor

I just want to know as i have tried above with a sleep of 5 seconds, but getting outStream.println in fraction of second. So I just want to understand if this is how Async annotation works i.e., if it has given the instant response and thread.sleep is executed by other thread.

Show us your method. I'm not sure I understand the behavior you are describing. — Sotirios Delimanolis, Mar 18 '14 at 15:26

score 1 · Accepted Answer · answered Apr 18 '14 at 08:46

Assuming your method is like this

@Async
public void foo() {
    sleep(5000L);
    System.out.println("hello world");
}

This won't tell you anything as the 5sec wait is in another thread anyway. However if you have something like this

public void bar() {
    myService.foo();
    System.out.println("hello world");
}

Then if you get Hello World in "a fraction of second", it means that the invocation of foo has been indeed done asynchronously.

When you invoke a method with @Async the method invocation is wrapped in a Callable and that instance is passed to the executor service using the submit method.

If the executor cannot process the method execution, you'll get a TaskRejectedException. For instance, if your ThreadPoolTaskExecutor has a pool size of 2 threads and a queue size of 0, the third invocation of the foo method will fail with a TaskRejectedException if the pool threads are still busy processing the two first invocations.

@Async with outstream and thread.sleep method

1 Answers1