线程状态转换

2023-10-29 21:14:10

@Test
public void testThreadState1() throws Exception {
    Thread thread4TestState = new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println("1" + "-" + Thread.currentThread().getName() + "的状态是:" + Thread.currentThread().getState());
        }
    },"thread4TestState");
    System.out.println("2" + "-" + thread4TestState.getName() + "的状态是:" + thread.getState());
    thread.start();
    System.out.println("3" + "-" + thread4TestState.getName() + "的状态是:" + thread.getState());
    Thread.sleep(2000);
    System.out.println("4" + "-" + thread4TestState.getName() + "的状态是:" + thread.getState());
    System.in.read();
}

上面的输出是：

new一个新的线程，没有调用start()；

输出：2-thread4TestState的状态是:NEW
调用start()；

输出：3-thread4TestState的状态是:RUNNABLE
在run()方法里；

输出：1-thread4TestState的状态是:RUNNABLE
run()执行完了；

输出：4-thread4TestState的状态是:TERMINATED

@Test
public void testThreadState2() throws Exception {
    Object lock = new Object();
    Thread thread4TestState1 = new Thread(new Runnable() {
        @Override
        public void run() {
            synchronized (lock){
                System.out.println("1" + "-" + Thread.currentThread().getName() + "获取到了锁，当前的状态是:" + Thread.currentThread().getState());
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.println("2" + "-" + Thread.currentThread().getName() + "释放了锁，当前的状态是:" + Thread.currentThread().getState());
        }
    }, "thread4TestState1");
    Thread thread4TestState2 = new Thread(new Runnable() {
        @Override
        public void run() {
            synchronized (lock){
                System.out.println("3" + "-" + Thread.currentThread().getName() + "获取到了锁，当前的状态是:" + Thread.currentThread().getState());
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            System.out.println("4" + "-" + Thread.currentThread().getName() + "释放了锁，当前的状态是:" + Thread.currentThread().getState());
        }
    }, "thread4TestState2");

    thread4TestState1.start();
    thread4TestState2.start();
    Thread.sleep(500);
    System.out.println("5" + "-" + thread4TestState1.getName() + "当前的状态是:" + thread4TestState1.getState());
    System.out.println("6" + "-" + thread4TestState2.getName() + "当前的状态是:" + thread4TestState2.getState());
    System.in.read();

}

上面的输出是：

首先thread4TestState1获取到锁，进入同步代码块；

输出：1-thread4TestState1获取到了锁，当前的状态是:RUNNABLE
然后，thread4TestState1睡1000ms，

那在500ms时查看，由于调用了sleep()

thread4TestState1的状态就是TIMED_WAITING；

输出：5-thread4TestState1当前的状态是:TIMED_WAITING
而thread4TestState2由于thread4TestState1还没睡醒，所以还没释放锁，那thread4TestState2也就还在等待获取锁，所以状态就是BLOCKED

输出：6-thread4TestState2当前的状态是:BLOCKED
1000ms过去了，thread4TestState1睡醒了，释放了锁，状态还是RUNNABLE

输出：2-thread4TestState1释放了锁，当前的状态是:RUNNABLE
由于thread4TestState1释放了锁，那thread4TestState2就可以拿到锁，状态从BLOCKED变为RUNNABLE

输出：3-thread4TestState2获取到了锁，当前的状态是:RUNNABLE
输出：4-thread4TestState2释放了锁，当前的状态是:RUNNABLE

@Test
public void testThreadState3() throws Exception {
    Object lock = new Object();
    Thread thread4TestState1 = new Thread(new Runnable() {
        @Override
        public void run() {
            synchronized (lock){
                System.out.println("1" + "-" + Thread.currentThread().getName() + "获取到了锁，当前的状态是:" + Thread.currentThread().getState());
                try {
                    lock.wait(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("2" + "-" + Thread.currentThread().getName() + "即将释放锁，当前的状态是:" + Thread.currentThread().getState());
            }
        }
    }, "thread4TestState1");

    thread4TestState1.start();
    Thread.sleep(300);
    System.out.println("3" + "-" + thread4TestState1.getName() + "当前的状态是:" + thread4TestState1.getState());
    System.in.read();
}

上面的输出是：

首先获取到了锁

输出：1-thread4TestState1获取到了锁，当前的状态是:RUNNABLE
获取到锁的线程调用了wait(timeout)

输出：3-thread4TestState1当前的状态是:TIMED_WAITING
线程从TIMED_WATING状态恢复

输出：2-thread4TestState1即将释放锁，当前的状态是:RUNNABLE

@Test
public void testThreadState3() throws Exception {
    Object lock = new Object();
    Thread thread4TestState1 = new Thread(new Runnable() {
        @Override
        public void run() {
            synchronized (lock){
                System.out.println("1" + "-" + Thread.currentThread().getName() + "获取到了锁，当前的状态是:" + Thread.currentThread().getState());
                try {
                    lock.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("2" + "-" + Thread.currentThread().getName() + "即将释放锁，当前的状态是:" + Thread.currentThread().getState());
            }
        }
    }, "thread4TestState1");

    thread4TestState1.start();
    Thread.sleep(50);
    System.out.println("3" + "-" + thread4TestState1.getName() + "当前的状态是:" + thread4TestState1.getState());
    synchronized (lock){
        lock.notify();
    }
    System.out.println("4" + "-" + thread4TestState1.getName() + "当前的状态是:" + thread4TestState1.getState());
    System.in.read();
}

上面的输出是：

首先获取到了锁

输出：1-thread4TestState1获取到了锁，当前的状态是:RUNNABLE
线程调用了无参的wait()

输出：3-thread4TestState1当前的状态是:WAITING
主线程执行了notify操作，唤醒处于WAITING的线程，输出有可能是RUNNABLE或者BLOCKED

输出：4-thread4TestState1当前的状态是:RUNNABLE或者BLOCKED
输出：2-thread4TestState1即将释放锁，当前的状态是:RUNNABLE

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