java - Phaser 作为 CountdownLatch 的替代品

Question

使用 Phaser 替代 CountdownLatch 在性能、内存、改进、稳健性等方面是否有任何好处？

例如，myCountDownLatch() 的行为与 myPhaser() 相同:

带有 CountdownLatch 的版本 1:

public static void myCountDownLatch() {

        CountDownLatch countDownLatch = new CountDownLatch(1);
        Thread t = new Thread(() ->
        {
            try {
                log.info("CountDownLatch: in thread..");
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            countDownLatch.countDown();
        });
        t.start();
        try {
            countDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        log.info("CountDownLatch: out thread..");
    }

带有 Phaser 的版本 2:

public static void myPhaser() {

        Phaser phaser = new Phaser(1);
        Thread t = new Thread(() ->
        {
            try {
                log.info("phaser: in thread..");
                Thread.sleep(3000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            phaser.arriveAndDeregister();
        });
        t.start();
        // 1. benefit: With phaser we dont need to manage the InterruptedException ourselves.
        phaser.arriveAndAwaitAdvance();
        log.info("phaser: out thread..");

    }

或者java中的CountdownLatch有更好的替代品吗？

Answer 1

来自https://www.infoq.com/news/2008/07/phasers/

Performance results obtained from a portable implementation of phasers on three different SMP platforms demonstrate that they can deliver superior performance to existing barrier implementations, in addition to the productivity benefits that result from their generality and safety properties.

更多详情请查看JSR 166