Dining 철학자가 Java에서 접근 방식을 모니터링합니다. 인터리브 스레드가 실행되지 않습니다.

Question

Silberschatz의 솔루션을 기반으로 Dining Philosopher 문제에 대한 모니터를 구현할 때 스레드 인터리빙 된 실행이 수행되지 않은 것처럼 보입니다. 부적절한 것을 차단 했습니까? 하드웨어 문제입니까? 왜냐하면 이제 모든 철학자들이 올바른 순서로 먹기 때문입니다.

public class DiningPhilosophersMonitor { 

public static final int NB_OF_PHILOSOPHERS = 5; 

private enum State {THINKING, HUNGRY, EATING} 
private State[] states = new State[NB_OF_PHILOSOPHERS]; 
private Object[] self = new Object[NB_OF_PHILOSOPHERS]; 

public DiningPhilosophersMonitor() { 

    for (int i=0; i<NB_OF_PHILOSOPHERS; i++) { 
     this.states[i] = State.THINKING; 
     System.out.println("Philosopher " + i + " is " + "THINKING"); 
     this.self[i] = new Object(); 
    } 
} 

public synchronized void takeForks(int i) { 
    this.states[i] = State.HUNGRY; 
    System.out.println("Philosopher " + i + " is " + "HUNGRY"); 

    test(i); 

    if (this.states[i] != State.EATING) { 
     try { 
      System.out.println("Philosopher " + i + " is " + "WAITING"); 

      synchronized (this.self[i]) { 
       this.self[i].wait(); 
      } 

     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
    } 
} 

public synchronized void returnForks(int i) { 
    this.states[i] = State.THINKING; 
    System.out.println("Philosopher " + i + " is " + "THINKING"); 

    test((i+NB_OF_PHILOSOPHERS-1) % NB_OF_PHILOSOPHERS); 
    test((i+1) % NB_OF_PHILOSOPHERS); 
} 

private void test(int i) { 
    if (
      this.states[(i+NB_OF_PHILOSOPHERS-1) % NB_OF_PHILOSOPHERS] != State.EATING && 
      this.states[i] == State.HUNGRY && 
      this.states[(i+1) % NB_OF_PHILOSOPHERS] != State.EATING 
     ) { 

     this.states[i] = State.EATING; 
     System.out.println("Philosopher " + i + " is " + "EATING"); 

     synchronized (this.self[i]) { 
      this.self[i].notifyAll(); 
     } 
    } 
} 
} 

public class Philosopher implements Runnable { 

private DiningPhilosophersMonitor monitor; 
private int i; 

public Philosopher(DiningPhilosophersMonitor monitor, int i) { 
    this.monitor = monitor; 
    this.i = i; 
} 

@Override 
public void run() { 
    for (int j=0; j<10; j++) { 

     monitor.takeForks(i); 

     SleepUtilities.nap(); 

     monitor.returnForks(i); 
    } 
} 
} 

public class Init { 

public static void main(String[] args) { 
    DiningPhilosophersMonitor monitor = new DiningPhilosophersMonitor(); 
    for (int i=0; i<DiningPhilosophersMonitor.NB_OF_PHILOSOPHERS; i++) { 
     new Thread(new Philosopher(monitor, i)).run(); 
    } 
} 
} 

public class SleepUtilities 
{ 
public static void nap() { 
    nap(NAP_TIME); 
} 

public static void nap(int duration) { 
     int sleeptime = (int) (NAP_TIME * Math.random()); 
     try { Thread.sleep(sleeptime*1000); } 
     catch (InterruptedException e) {} 
} 

private static final int NAP_TIME = 5; 
} 

Answer 1

스레드의 start() 메소드를 호출해야합니다. run()을 호출하면 호출 스레드에 의해 실행됩니다.

은 그래서 참 바보 같은 실수, 빠른 지원

new Thread(new Philosopher(monitor, i)).start();