生产者消费者问题（thinking in java 709 ）

scaoping

　　一个跳不出的死循环出现在生产者消费者问题上


import java.util.concurrent.*;
class Meal {
private final int orderNum;
public Meal(int orderNum) {
this.orderNum = orderNum;
}
public String toString() {
return "Meal" + orderNum;
}
}
class WaitPerson implements Runnable {
private Restaurant restaurant;
public WaitPerson(Restaurant r) {
restaurant = r;
}
public void run() {
try {
while (!Thread.interrupted()) {
synchronized (this) {
while (restaurant.meal == null)
wait();
}
}
System.out.println("Waitpersion got " + restaurant.meal);
synchronized (restaurant.chef) {
restaurant.meal = null;
restaurant.chef.notifyAll();
}
} catch (InterruptedException e) {
System.out.println("WaitPerson interrupted");
}
}
}
class Chef implements Runnable {
private Restaurant restaurant;
private int count = 0;
public Chef(Restaurant r) {
restaurant = r;
}
public void run() {
try {
while (!Thread.interrupted()) {
synchronized (this) {
while (restaurant.meal != null)
wait();
}
if (++count == 10) {
System.out.println("Out of food,closing");
restaurant.exec.shutdownNow();
}
System.out.print("Order up! ");
synchronized (restaurant.waitPerson) {
restaurant.meal = new Meal(count);
restaurant.waitPerson.notifyAll();
}
TimeUnit.MILLISECONDS.sleep(100);
}
} catch (InterruptedException e) {
System.out.printf("Chef interrupted");
}
}
}
public class Restaurant {
Meal meal;
ExecutorService exec = Executors.newCachedThreadPool();
WaitPerson waitPerson = new WaitPerson(this);
Chef chef = new Chef(this);
public Restaurant() {
exec.execute(chef);
exec.execute(waitPerson);
}
public static void main(String[] args) {
new Restaurant();
}
}

　　问题出现在哪？WaitPerson的run得到资源有被卷入外层的while。就这么一点点耽误我好几小时。。。

应该是这样


while (!Thread.interrupted()) {
synchronized (this) {
while (restaurant.meal == null)
wait();
}
System.out.println("Waitpersion got " + restaurant.meal);
synchronized (restaurant.chef) {
restaurant.meal = null;
restaurant.chef.notifyAll();
}
}