Java 多线程实现死锁场景

简述：

《Java 编程思想》  P718 ~ P722

模拟死锁的场景， 三个人 三根筷子，每个人需要拿到身边的两根筷子才能开始吃饭

出现死锁的场景是，三个人都拿到了右边的筷子，但是由于筷子都被抢占，均无法获得左边的筷子

Chopstick.java

package com.anialy.test.multithread.philosophers;

public class Chopstick {
	private boolean taken = false;
	
	public synchronized void take() throws InterruptedException{
		while(taken)
			wait();
		taken = true;
	}
	
	public synchronized void drop(){
		taken = false;
	}
}

Philosopher.java

package com.anialy.test.multithread.philosophers;

import java.util.concurrent.TimeUnit;

public class Philosopher implements Runnable {

	private Chopstick left; // 左边的筷子

	private Chopstick right; // 右边的筷子

	public Philosopher(Chopstick left, Chopstick right){
		this.left = left;
		this.right = right;
	}
	
	private void pause() throws InterruptedException {
		TimeUnit.MILLISECONDS.sleep(100);
	}

	private void pauseToHoldChopstick() throws InterruptedException {
		TimeUnit.MILLISECONDS.sleep(1000);
	}

	public void run() {
		try {
			while(!Thread.interrupted()) {
				System.out.println(this + " thinking");
				pause();
				right.take();
				System.out.println(this + " grabbing right");
				// 当一个人拿起了一根筷子, 停顿一段时间，让别人也抢到各自右边的筷子
				pauseToHoldChopstick();
				left.take();
				System.out.println(this + " grabbing left");
				System.out.println(this + " eating");
				pause();
				// 完成之后放下筷子
				right.drop();
				System.out.println(this + " drop right");
				left.drop();
				System.out.println(this + " drop left");
			}
		} catch (InterruptedException e){
			System.out.println(this + " exiting via interrupt");
		}
	}


}

死锁测试函数

DeadLockTest.java

package com.anialy.test.multithread.philosophers;

import java.io.IOException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

public class DeadLockTest {
	public static void main(String[] args) throws InterruptedException, IOException {
		int size = 3;
		
		ExecutorService exec = Executors.newCachedThreadPool();
		Chopstick[] sticks = new Chopstick[size];
		for(int i=0; i

测试如图，在每个线程拿到右边的筷子之后，都进入死锁等待状态