What advantage is there to using Spring @Async vs. CompleteableFuture directly?
Solution 1
Your application is managed by the container. Since it's discouraged to spawn Thread
s on you own, you can let the container inject a managed Executor
.
@Service
class MyService {
@Autowired
private Executor executor;
public CompletableFuture<?> compute() {
return CompletableFuture.supplyAsync(() -> /* compute value */, executor);
}
}
Solution 2
There is no “vs.” between the two – these are complementary technologies:
-
CompletableFuture
provides a convenient way to chain different stages of asynchronous computation – with more flexibility than Spring'sListenableFuture
; -
@Async
provides convenient management of your background tasks and threads, with standard Spring configuration for your executor(s).
But both can be combined (since Spring 4.2). Suppose you want to turn the following method into a background task returning a CompletableFuture
:
public String compute() {
// do something slow
return "my result";
}
What you have to do:
- if not already done: configure your application with
@EnableAsync
and anExecutor
bean - annotate the method with
@Async
- wrap its result into
CompletableFuture.completedFuture()
@Async
public CompletableFuture<String> computeAsync() {
// do something slow - no change to this part
// note: no need to wrap your code in a lambda/method reference,
// no need to bother about executor handling
return CompletableFuture.completedFuture("my result");
}
As you notice, you don't have to bother about submitting the background task to an executor: Spring takes care of that for you. You only have to wrap the result into into a completed CompletableFuture
so that the signature matches what the caller expects.
In fact, this is equivalent to:
@Autowire
private Executor executor;
public CompletableFuture<String> computeAsync() {
return CompletableFuture.supplyAsync(() -> {
// do something slow
return "my result";
}, executor);
}
but it removes the need to:
- inject the executor
- deal with the executor in a
supplyAsync()
call - wrap the logic in a lambda (or extract it to a separate method)
Christian Bongiorno
Software engineering leader with a patent and over 15 years combined software development experience. I truly enjoy collaborating with others and mentoring Junior developers while working with the product team to build world class software. You can find samples of my work: https://github.com/chb0github/ And my linked in profile: http://www.linkedin.com/pub/christian-bongiorno/3/282/732 My patent: http://www.google.com/patents/US8495068
Updated on June 02, 2022Comments
-
Christian Bongiorno almost 2 years
What's the advantage of using Spring Async vs. Just returning the
CompletableFuture
on your own?