CountDownLatch demo

CountDownLatchTest.java

package org.nkcoder.module.javatest.concurrent;

import java.time.Duration;
import java.time.Instant;
import java.util.Random;
import java.util.concurrent.CountDownLatch;

/**
 * created by daniel at 12/15/16 21:45
 */
public class CountDownLatchTest {

    public static void main(String[] args) {
        CountDownLatchTest latchTest = new CountDownLatchTest();

        int workers = 20;
        Random r = new Random(Instant.now().getEpochSecond());

        final CountDownLatch startGate = new CountDownLatch(1);
        final CountDownLatch endGate = new CountDownLatch(workers);

        for (int i = 0; i < workers; i++) {
            new Thread(() -> {
                System.out.println("thread: " + Thread.currentThread().getName() + "...");
                try {
                    startGate.await();
                } catch (InterruptedException e) {
                    System.out.println("thread: " + Thread.currentThread().getName() + e);
                    Thread.currentThread().interrupt();
                }
                latchTest.getFibonacci(r.nextInt(Integer.MAX_VALUE / 2));
                endGate.countDown();
            }).start();
        }
        System.out.println("thread: " + Thread.currentThread().getName() + "start...");
        Instant begin = Instant.now();
        startGate.countDown();
        try {
            endGate.await();
        } catch (InterruptedException e) {
            System.out.println("thread: " + Thread.currentThread().getName() + e);
            Thread.currentThread().interrupt();
        }
        Instant end = Instant.now();
        System.out.println("thread: " + Thread.currentThread().getName() + "end...");
        Duration duration = Duration.between(begin, end);
        System.out.println("duration(s): " + duration.getSeconds());
    }

    private long getFibonacci(final long num) {
        if (num == 1 || num == 2) {
            return num;
        }
        long f1 = 1;
        long f2 = 2;
        for (long i = 3; i <= num; i++) {
            long f = f1 + f2;
            f1 = f2;
            f2 = f;
        }
        System.out.println("num: " + num + ", fibonacci: " + f2);
        return f2;
    }
}