多线程死锁发生情景之一:同步的嵌套

Posted 2020-10-01 晴空半岛

/*
　　死锁：常见情景之一：同步的嵌套。

*/
class Ticket implements Runnable {
    private  int num = 100;
    Object obj = new Object();
    boolean flag = true;
    public void run() {
        if(flag) {
            while(true) {
                synchronized(obj) {
                    show();
                }
            }        
        }
            
        else {        
            while(true) {
                this.show();
            }        
        }         
                
    }

    public synchronized void show() {

        synchronized(obj) {
            if(num>0) {
                try{Thread.sleep(10);}catch (InterruptedException e){}
                
                System.out.println(Thread.currentThread().getName()+".....sale...."+num--);
            }
        }
    }
}


class DeadLockDemo {

    public static void main(String[] args) {
        Ticket t = new Ticket();
        Thread t1 = new Thread(t);
        Thread t2 = new Thread(t);

        t1.start();
        try{Thread.sleep(10);}catch(InterruptedException e){}
        t.flag = false;
        t2.start();
    }
}