CODEWITHSUNDEEP
rx-java
Diamond
Diamond

Reputation: 237

Why doesn't main thread wait for the completion of the Scheduler threads?

public static void main(String[] args) throws InterruptedException {
    Observable.range(1, 3)
    .subscribeOn(Schedulers.computation())
    .map(i-> compute(i))  
    .subscribe(i -> {
        System.out.println(i);
    });
    System.out.println("last line");

}

public static int compute(Integer i) {
    try {
        System.out.println("compute integer i: " + i);          
        Thread.sleep(1000);         
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    return 10*i;
}

Output:

last line
compute integer i: 1

If the main method would start a usual thread we would see the complete output:

public static void main(String[] args) {
    Thread a=new Thread(() -> {

            compute(1); 
            compute(2); 
            compute(3); 
    });

    a.start();
    System.out.println("last line");
}

Output:

last line
compute integer i: 1
compute integer i: 2
compute integer i: 3

Why doesnt the main thread wait for the completion of Schedulers.computation() thread whereas it waits for the completion of the usual new Thread()?

Upvotes: 1

Views: 257

Answers (1)

akarnokd
akarnokd

Reputation: 69997

This is by design. RxJava standard schedulers use daemon threads so that they don't prevent the JVM from quitting. That means you have to keep non-daemon thread(s) running in some form if you want the work on schedulers to finish.

Upvotes: 2

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