获取synchronized锁中的阻塞队列中的线程是非公平的-白红宇

synchronized中阻塞队列的线程是非公平的

测试demo:

import java.text.MessageFormat;import java.text.SimpleDateFormat;import java.util.Date;import java.util.concurrent.TimeUnit;public class SleepState {    public static ThreadLocal
     
       threadLocal = new ThreadLocal
      
       () {        @Override        protected SimpleDateFormat initialValue() {            return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSSZ");        }    };    private static final int[] lock = new int[0];    public static void main(String[] args) throws InterruptedException {        Thread thread1 = new Thread(new TestSynchronizedTask(lock, 1000 * 10), "Thread1");        Thread thread2 = new Thread(new TestSynchronizedTask(lock, 10), "Thread2");        Thread thread3 = new Thread(new TestSynchronizedTask(lock, 1000), "Thread3");        thread1.start();        TimeUnit.MILLISECONDS.sleep(1000);        thread2.start();        TimeUnit.MILLISECONDS.sleep(1000);        thread3.start();    }}class TestSynchronizedTask implements Runnable {    private final int[] lock;    private int sleepMilliSeconds;    public TestSynchronizedTask(int[] lock, int sleepMilliSeconds) {        this.lock = lock;        this.sleepMilliSeconds = sleepMilliSeconds;    }    public TestSynchronizedTask(int[] lock) {        this(lock, 0);    }    @Override    public void run() {        synchronized (lock) {            try {                System.out.println(MessageFormat.format(" {0} {1}  begin", SleepState.threadLocal.get().format(new Date()), Thread.currentThread()));                TimeUnit.MILLISECONDS.sleep(sleepMilliSeconds);                System.out.println(MessageFormat.format("{0} {1}  will end", SleepState.threadLocal.get().format(new Date()), Thread.currentThread()));            } catch (InterruptedException e) {                e.printStackTrace();            }        }    }}

执行结果： 2016-05-26 13:31:44.260+0800 Thread[Thread1,5,main]  begin2016-05-26 13:31:54.260+0800 Thread[Thread1,5,main]  will end 2016-05-26 13:31:54.260+0800 Thread[Thread3,5,main]  begin2016-05-26 13:31:55.260+0800 Thread[Thread3,5,main]  will end 2016-05-26 13:31:55.260+0800 Thread[Thread2,5,main]  begin2016-05-26 13:31:55.276+0800 Thread[Thread2,5,main]  will end