java中的哲学家吃饭导致死锁
我已经用java解决了这个问题,但出现了一些问题,导致了死锁。。。 有人能找出这导致僵局的原因吗 哲学家们在餐厅里应该永远是N-1,这样每个人都可以吃饭,防止饥饿 主要类别:java中的哲学家吃饭导致死锁,java,multithreading,deadlock,dining-philosopher,Java,Multithreading,Deadlock,Dining Philosopher,我已经用java解决了这个问题,但出现了一些问题,导致了死锁。。。 有人能找出这导致僵局的原因吗 哲学家们在餐厅里应该永远是N-1,这样每个人都可以吃饭,防止饥饿 主要类别: public class DiningPhilosophers { public static int N = 5; //Philosopher philosopher[]; //Chopsticks chopsticks; //DiningRoom diningroom; public static void ma
public class DiningPhilosophers {
public static int N = 5;
//Philosopher philosopher[];
//Chopsticks chopsticks;
//DiningRoom diningroom;
public static void main(String[] args) {
Philosopher[] philosopher = new Philosopher[N];
Chopsticks chopsticks = new Chopsticks(N);
DiningRoom diningroom = new DiningRoom(N);
for(int i = 0;i<N;i++)
philosopher[i] = new Philosopher(i,10,20,30,100,chopsticks,diningroom);
for(int i = 0;i<N;i++)
philosopher[i].start();
}
}
哲学家班:
class Philosopher extends Thread{
int i;
int minThinkTime,maxThinkTime,minEatTime,maxEatTime;
private Chopsticks c;
private DiningRoom d;
public Philosopher(int index,int minThinkTime,int maxThinkTime,int minEatTime,int maxEatTime, Chopsticks chopsticks, DiningRoom diningroom){
this.i = index;
this.minThinkTime = minThinkTime;
this.maxThinkTime = maxThinkTime;
this.minEatTime = minEatTime;
this.maxEatTime = maxEatTime;
this.c = chopsticks;
this.d = diningroom;
}
public void think(){
try{
System.out.println(i+" Philosopher is thinking!");
Thread.sleep((int)(Math.random()*(maxThinkTime - minThinkTime))+minThinkTime);
}catch(InterruptedException e){
}
}
public void eat(){
try{
System.out.println(i+" Philosopher is eating!");
Thread.sleep((int)(Math.random()*(maxEatTime - minEatTime))+minEatTime);
}catch(InterruptedException e){
}
}
public void run() {
while (true) {
think();
System.out.println("pholosopher "+i+"entering");
d.enter();
c.take(i);
eat();
c.release(i);
d.exit();
System.out.println("pholosopher "+i+"exiting");
}
}
}
在:
public synchronized void take(int哲学家)
你应该把减少筷子计数器的线移到圈外。我认为你的筷子.take()是错误的。现在,当一个哲学家一开始拿筷子时,它什么也不做。然后,当他释放chospticks时,他的邻居的numOfChops会增加,并且永远不等于2,所以他们都会阻塞take() 您已经将卷括号从while放在take()的末尾,它应该放在这里:
public synchronized void take(int philosopher){
while(numOfChops[philosopher] != 2){
try{
wait();
}catch(InterruptedException e){
}
}
//System.out.println("philosopher "+philosopher+"taking");
numOfChops[(philosopher+1)%N]--;
numOfChops[(Math.abs(philosopher-1))%N]--;
}
@stelios看起来你在餐厅也犯了同样的错误#enter()下面的答案可能已经修复了你的僵局,但我担心你使用了
(Math.abs(哲学家-1))%N
。这不会在N上实现响铃。您需要使用(哲学家-1+N)%N
来正确响铃,因为您需要0-1
来评估N-1
。同样餐厅。退出可能应该使用通知所有人筷子。释放而不仅仅是通知。或许不是。。。我现在不确定(
class Philosopher extends Thread{
int i;
int minThinkTime,maxThinkTime,minEatTime,maxEatTime;
private Chopsticks c;
private DiningRoom d;
public Philosopher(int index,int minThinkTime,int maxThinkTime,int minEatTime,int maxEatTime, Chopsticks chopsticks, DiningRoom diningroom){
this.i = index;
this.minThinkTime = minThinkTime;
this.maxThinkTime = maxThinkTime;
this.minEatTime = minEatTime;
this.maxEatTime = maxEatTime;
this.c = chopsticks;
this.d = diningroom;
}
public void think(){
try{
System.out.println(i+" Philosopher is thinking!");
Thread.sleep((int)(Math.random()*(maxThinkTime - minThinkTime))+minThinkTime);
}catch(InterruptedException e){
}
}
public void eat(){
try{
System.out.println(i+" Philosopher is eating!");
Thread.sleep((int)(Math.random()*(maxEatTime - minEatTime))+minEatTime);
}catch(InterruptedException e){
}
}
public void run() {
while (true) {
think();
System.out.println("pholosopher "+i+"entering");
d.enter();
c.take(i);
eat();
c.release(i);
d.exit();
System.out.println("pholosopher "+i+"exiting");
}
}
}
public synchronized void take(int philosopher){
while(numOfChops[philosopher] != 2){
try{
wait();
}catch(InterruptedException e){
}
}
//System.out.println("philosopher "+philosopher+"taking");
numOfChops[(philosopher+1)%N]--;
numOfChops[(Math.abs(philosopher-1))%N]--;
}