默認使用的線程池
不傳executor時默認使用ForkJoinPool.commonPool()
IntStream.range(0, 15).parallel().forEach(i -> {
System.out.println(Thread.currentThread());
});
輸出
Thread[ForkJoinPool.commonPool-worker-1,5,main]
Thread[main,5,main]
Thread[ForkJoinPool.commonPool-worker-1,5,main]
Thread[ForkJoinPool.commonPool-worker-3,5,main]
Thread[ForkJoinPool.commonPool-worker-2,5,main]
Thread[ForkJoinPool.commonPool-worker-3,5,main]
Thread[ForkJoinPool.commonPool-worker-1,5,main]
Thread[main,5,main]
Thread[ForkJoinPool.commonPool-worker-1,5,main]
Thread[ForkJoinPool.commonPool-worker-3,5,main]
Thread[ForkJoinPool.commonPool-worker-2,5,main]
Thread[ForkJoinPool.commonPool-worker-3,5,main]
Thread[ForkJoinPool.commonPool-worker-1,5,main]
Thread[main,5,main]
Thread[ForkJoinPool.commonPool-worker-2,5,main]
- commonPool
This pool is statically constructed; its run state is unaffected by attempts to shutdown() or shutdownNow(). However this pool and any ongoing processing are automatically terminated upon program System.exit(int). Any program that relies on asynchronous task processing to complete before program termination should invoke commonPool().awaitQuiescence, before exit.
thenRun測試實例1
不設定executor
@Test
public void testRunOnCommonPool() throws InterruptedException {
CompletionStage<Void> futurePrice = CompletableFuture.runAsync(() -> {
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("test1:1 - runAsync(runnable), job thread: " + Thread.currentThread());
//Thread[ForkJoinPool.commonPool-worker-1,5,main]
}
);
System.out.println("test1:flag1");
futurePrice.thenRun(() -> {
System.out.println("test1:2 - thenRun(runnable)), action thread: " + Thread.currentThread());
//Thread[ForkJoinPool.commonPool-worker-1,5,main]
});
System.out.println("test1:flag2");
futurePrice.thenRunAsync(() -> {
System.out.println("test1:3 - thenRunAsync(runnable), action thread: " + Thread.currentThread());
//Thread[ForkJoinPool.commonPool-worker-1,5,main]
});
TimeUnit.SECONDS.sleep(100);
}
輸出
test1:flag1
test1:flag2
test1:1 - runAsync(runnable), job thread: Thread[ForkJoinPool.commonPool-worker-1,5,main]
test1:2 - thenRun(runnable)), action thread: Thread[ForkJoinPool.commonPool-worker-1,5,main]
test1:3 - thenRunAsync(runnable), action thread: Thread[ForkJoinPool.commonPool-worker-1,5,main]
設定executor
@Test
public void testRunOnExecutors() throws InterruptedException {
CompletionStage<Void> futurePrice = CompletableFuture.runAsync(() -> {
try {
TimeUnit.SECONDS.sleep(1);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("test2:1 - runAsync(runnable, executor), job thread: " + Thread.currentThread());
//Thread[pool-1-thread-1,5,main]
}, executor);
System.out.println("test2:flag1");
futurePrice.thenRunAsync(() -> {
System.out.println("test2:2 - thenRunAsync(runnable), action thread: " + Thread.currentThread());
//Thread[pool-1-thread-1,5,main]
});
System.out.println("test2:flag2");
futurePrice.thenRun(() -> {
System.out.println("test2:3 - thenRun(runnable), action thread: " + Thread.currentThread());
//Thread[pool-1-thread-2,5,main]
});
futurePrice.thenRunAsync(() -> {
System.out.println("test2:4 - thenRunAsync(runnable, executor), action thread: " + Thread.currentThread());
//Thread[ForkJoinPool.commonPool-worker-1,5,main]
}, executor);
TimeUnit.SECONDS.sleep(100);
}
輸出
test2:flag1
test2:flag2
test2:1 - runAsync(runnable, executor), job thread: Thread[pool-1-thread-1,5,main]
test2:3 - thenRun(runnable), action thread: Thread[pool-1-thread-1,5,main]
test2:4 - thenRunAsync(runnable, executor), action thread: Thread[pool-1-thread-2,5,main]
test2:2 - thenRunAsync(runnable), action thread: Thread[ForkJoinPool.commonPool-worker-1,5,main]
thenRun測試實例2
沒有sleep
@Test
public void testThenRun(){
CompletableFuture<String> f1 = CompletableFuture.supplyAsync(() -> {
System.out.println("f1 thread:"+Thread.currentThread().getName());
return "zero";
}, executor);
f1.thenRun(new Runnable() {
@Override
public void run() {
System.out.println("then run thread:"+Thread.currentThread().getName());
System.out.println("finished");
}
});
TimeUnit.SECONDS.sleep(10);
}
- 使用executor的輸出
f1 thread:pool-1-thread-1
then run thread:main
finished
- 不使用executor的輸出
f1 thread:ForkJoinPool.commonPool-worker-1
then run thread:main
finished
加上sleep
CompletableFuture<String> f1 = CompletableFuture.supplyAsync(() -> {
System.out.println("f1 thread:"+Thread.currentThread().getName());
try {
TimeUnit.SECONDS.sleep(2);
} catch (InterruptedException e) {
e.printStackTrace();
}
return "zero";
}, executor);
f1.thenRun(new Runnable() {
@Override
public void run() {
System.out.println("then run thread:"+Thread.currentThread().getName());
System.out.println("finished");
}
});
TimeUnit.SECONDS.sleep(10);
- 使用executor的輸出
f1 thread:pool-1-thread-1
then run thread:pool-1-thread-1
finished
- 不使用executor的輸出
f1 thread:ForkJoinPool.commonPool-worker-1
then run thread:ForkJoinPool.commonPool-worker-1
finished
小結
不帶 async 的 thenRun() 方法仍然是一個異步方法，可能是使用main線程馅精，commonPool的線程或者是executor的線程闲孤。
