Java concurrency tool LockSupport

Java concurrency tool LockSupport
LockSupport

In the J. U. C framework, there is a class called LockSupport, which can accurately block and wake up specific threads and serve as the primitives of other synchronization classes.
LockSupport includes a park (Object blocker) and an unpark (Object blocker) method for blocking and wakeup, respectively.

For example, the following code contains a thread thread1 and a main thread. In thread1, the park method is called, The unpark method is called in the main thread, and the thread1 status is printed:

import java.util.concurrent.locks.LockSupport;public class Main{    public static void main(String[] args) throws InterruptedException {    Thread thread1 = new Thread(new Runnable() {        @Override        public void run() {        System.out.println(thread 1 start);        LockSupport.park(Thread.currentThread());        try {            Thread.sleep(4000);        } catch (InterruptedException e) {            e.printStackTrace();        }        System.out.println(thread 1 end);        }    });    thread1.start();    System.out.println(main thread start,thread1 +thread1.getState());    Thread.sleep(2000);    System.out.println(main thread running,thread1 +thread1.getState());    LockSupport.unpark(thread1);    Thread.sleep(6000);    System.out.println(main thread end,thread1 +thread1.getState());    }}

Execution result:

Thread 1 start
Main thread start, thread1 RUNNABLE
Main thread running, thread1 WAITING
Thread 1 end
Main thread end, thread1 TERMINATED

As you can see, thread1 becomes WAITTING after the park, and then wake up after the unpark and continue until the execution ends.