一个测试任务并发执行时间的方法

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import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;

/**
 * Created by xuyizhen on 2017/4/16.
 */
public class Util {
    /**
     * 测试任务task在指定的线程池execurtor中的并发度与性能的关系
     * 注意：线程池中的线程数必须不小于并发度，否则将导致线程饥饿死锁
     *
     * @param executor
     * @param concurrency
     * @param task
     * @return
     */
    public static long timeTest(Executor executor, int concurrency, final Runnable task) throws InterruptedException {
        final CountDownLatch allReady = new CountDownLatch(concurrency);
        final CountDownLatch start = new CountDownLatch(1);
        final CountDownLatch allOver = new CountDownLatch(concurrency);

        for (int i = 0; i < concurrency; i++) {
            executor.execute(new Runnable() {
                public void run() {
                    allReady.countDown();
                    try {
                        start.await();
                        task.run();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                        Thread.currentThread().interrupt();//使该断言能被Executor感知到
                    } finally {
                        allOver.countDown();
                    }
                }
            });
        }
        allReady.await();
        long startTime = System.nanoTime();
        start.countDown();
        allOver.await();
        long endTime = System.nanoTime();
        return endTime - startTime;
        //对于这种测试时间间隔的定时，要使用nanoTime而非currentTimeMills。因为前者更加准确并且不受实时时钟的影响。
    }
}