First of all, .getNow()
does not work, as this method requires a fall-back value as argument for the case the future is not completed yet. Since you are assuming the future to be completed here, you should also use join()
.
Then, there is no difference regarding thread exhaustion as in either case, you are waiting for the completion of all jobs before proceeding, potentially blocking the current thread.
The only way to avoid that, is by refactoring the code to not expect a result synchronously, but rather schedule the subsequent processing action to do done, when all jobs have been completed. Then, using allOf
becomes relevant:
final List<CompletableFuture<List<Test>>> completableFutures = resolvers.stream()
.map(resolver -> supplyAsync(() -> task.doWork()))
.collect(toList());
CompletableFuture.allOf(completableFutures.toArray(new CompletableFuture<?>[0]))
.thenAccept(justVoid -> {
// here, all jobs have been completed
final List<Test> tests = completableFutures.stream()
.flatMap(completableFuture -> completableFuture.join().stream())
.collect(toList());
// process the result here
});
By the way, regarding the toArray
method on collections, I recommended reading Arrays of Wisdom of the Ancients…
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…