idea java多线程问题

Question

public class MultithreadingTest {
public static void main(String[] args) {
SellTicket sellTicket = new SellTicket();
Thread thread1 = new Thread(sellTicket, "窗口1");
Thread thread2 = new Thread(sellTicket, "窗口2");
Thread thread3 = new Thread(sellTicket, "窗口3");
thread1.start();
thread2.start();
thread3.start();
}
}
public class SellTicket implements Runnable {
private int tickets = 100;
private Object o = new Object();
private int x = 0;
private Lock lock = new ReentrantLock();

@Override
public void run() {
    while (true) {

       
        lock.lock();
            if (tickets > 0) {
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName() + "正在出售第" + tickets + "张票");
                tickets--;
            lock.unlock();
      
        }
    }
}

}

为什么我运行的时候只有窗口1在动 我的jdk好像是18

Answer 1

首先，Reentrantlock默认使用非公平锁，可能导致其他线程永远无法获取到锁，造成线程“饥饿”现象。
private Lock lock = new ReentrantLock(true);这个就可以把ReentrantLock变成公平锁，但公平锁会损失一定性能