Java CompletableFuture 不取消底层执行

Question

我预计从下面的代码中，由于超时，可转换的未来将停止处理。但我可以看到取消没有任何影响。

public class CompletableFutureTest {

    public static void main(final String[] args) {
        ExecutorService executor = Executors.newFixedThreadPool(10);
        CompletableFuture completableFuture;
        CompletableFuture completableFuture2;
        completableFuture =
                CompletableFuture.runAsync(() -> callSomeMethod(1), executor);
        completableFuture2 =
                CompletableFuture.runAsync(() -> callSomeMethod(2), executor);
        try {

            System.out.println("After everything");
            completableFuture.get(2, TimeUnit.SECONDS);
            completableFuture2.get(2, TimeUnit.SECONDS);
        } catch (ExecutionException e) {
            cancelCompletableFuture(completableFuture);
            cancelCompletableFuture(completableFuture2);
        }  catch (TimeoutException e) {
            cancelCompletableFuture(completableFuture);
            cancelCompletableFuture(completableFuture2);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }

    }

    private static void callSomeMethod(int i) {
        System.out.println("In some method" + i);
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            System.out.println("Interrupted");
        }
        System.out.println("After sleep" + i);
    }

    private static void cancelCompletableFuture(CompletableFuture completableFuture) {
        completableFuture.cancel(true);
    }


}

我可以看到2个完全期货仍在运行。

Answer 1

CompletableFuture的javadoc可以回答您的问题，特别是取消方法的可能中断参数的注释：

此值在此实现中没有效果，因为中断不用于控制处理。