并发_查看运行时的线程信息

1. 打开终端
2. 输入命令jps, 结果示例:

35696 KotlinCompileDaemon
7812 Launcher
11880 ThreadState
14408
21064 Jps

3. 输入命令jstack #pid#, 这里是jstack 11880, 结果示例:

"BlockedThread-2" #12 prio=5 os_prio=0 tid=0x151af800 nid=0x50dc waiting for monitor entry [0x1568f000]
java.lang.Thread.State: BLOCKED (on object monitor)

"BlockedThread-1" #11 prio=5 os_prio=0 tid=0x151ab400 nid=0x5b64 waiting on condition [0x155ff000]
java.lang.Thread.State: TIMED_WAITING (sleeping)

"WaitingThread" #10 prio=5 os_prio=0 tid=0x151a6400 nid=0x8858 in Object.wait() [0x1556f000]
java.lang.Thread.State: WAITING (on object monitor)

"TimeWaitingThread" #9 prio=5 os_prio=0 tid=0x151a5c00 nid=0x5878 waiting on condition [0x154df000]
java.lang.Thread.State: TIMED_WAITING (sleeping)

代码

public class SleepUtils {
    public static void second(Long seconds) {
        try {
            TimeUnit.SECONDS.sleep(seconds);
        } catch (InterruptedException e) {
            e.printStackTrace();
            Thread.currentThread().interrupt();
        }
    }
}

public class ThreadState {

    public static void main(String[] args) {
        new Thread(new TimeWaiting(), "TimeWaitingThread").start();
        new Thread(new Waiting(), "WaitingThread").start();
        // 使用两个Blocked线程, 一个取锁成功, 另一个被阻塞
        new Thread(new Blocked(), "BlockedThread-1").start();
        new Thread(new Blocked(), "BlockedThread-2").start();
    }

    // 该线程不断的进行睡眠
    static class TimeWaiting implements Runnable {
        @Override
        public void run() {
            while (true) {
                SleepUtils.second(100L);
            }
        }
    }

    // 该线程在Waiting.class实例上等待
    static class Waiting implements Runnable {
        @Override
        public void run() {
            while (true) {
                synchronized (Waiting.class) {
                    try {
                        Waiting.class.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                        Thread.currentThread().interrupt();
                    }
                }
            }
        }
    }

    //改下线程在Blocked.class实例上加锁后, 不会释放该锁
    static class Blocked implements Runnable {
        @Override
        public void run() {
            synchronized (Blocked.class) {
                while (true) {
                    SleepUtils.second(100L);
                }
            }
        }
    }

}