CODEWITHSUNDEEP
javamultithreading
Zeeshan
Zeeshan

Reputation: 12431

How do I shut down executor when using it with CompletableFuture

Here I am invoking three threads, the second and third threads waits for the first thread to complete and then starts executing in parallel. If I use executor.shutdown() then only the first task executes. I want to know how to shutdown executor after all my threads are done executing

public static void main(String[] args) {
        System.out.println("In main");      
        ExecutorService executor = Executors.newFixedThreadPool(3);     
        CompletableFuture<Void> thenCompose = supplyAsync(() -> doTask1(), executor)
        .thenCompose(resultOf1 -> allOf(
                runAsync(() -> doTask2(resultOf1), executor),
                runAsync(() -> doTask3(), executor)
        ));
        //executor.shutdown();      
        System.out.println("Exiting main");
    }

    private static void doTask3() {
        for(int i=0; i<5;i++) {
            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.print(3);
        }

    }

    private static void doTask2(int num) {
        for(int i=0; i<5;i++) {
            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.print(num);
        }

    }

    private static int doTask1() {
        for(int i=0; i<5;i++) {
            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.print(1);
        }
        return 5;

    }

Output With executor.shutdown()

In main
Exiting main
11111

Output Without executor.shutdown()

In main
Exiting main
111113535353535
But the program doesn't terminates.

Upvotes: 3

Views: 5408

Answers (1)

Nadir
Nadir

Reputation: 1819

I would try by adding a final task to the CompletableFuture

.thenRun(() -> { executor.shutdown(); });

Upvotes: 9

Related Questions