Thread--生产者消费者假死分析

 package p_c_allWait;

 public class ValueObject {

     public static String value = "";

 }

 package p_c_allWait;

 public class P {

     private String lock;

     public P(String lock) {
         super();
         this.lock = lock;
     }

     public void setValue() {
         try {
             synchronized (lock) {
                 while(!ValueObject.value.equals("")) {
                     System.out.println("生产者 " + Thread.currentThread().getName() + " WAITING 了");
                     lock.wait();
                 }
                 System.out.println("生产者 " + Thread.currentThread().getName() + " RUNNABLE 了");
                 String value = System.currentTimeMillis() + "_" + System.nanoTime();
                 ValueObject.value = value;
                 lock.notify();
             }
         } catch (Exception e) {
             // TODO: handle exception
             e.printStackTrace();
         }
     }

 }

 package p_c_allWait;

 public class C {

     private String lock;

     public C(String lock) {
         super();
         this.lock = lock;
     }

     public void getValue() {
         try {
             synchronized (lock) {
                 while(ValueObject.value.equals("")) {
                     System.out.println("消费者 " + Thread.currentThread().getName() + " wating 了");
                     lock.wait();
                 }
                 System.out.println("消费者 " + Thread.currentThread().getName() + " RUNNABLE 了");
                 ValueObject.value = "";
                 lock.notify();
             }
         } catch (Exception e) {
             // TODO: handle exception
             e.printStackTrace();
         }
     }

 }

 package p_c_allWait;

 public class ThreadP extends Thread {

     private P p;

     public ThreadP(P p) {
         super();
         this.p = p;
     }

     @Override
     public void run() {
         while(true) {
             p.setValue();
         }
     }

 }

 package p_c_allWait;

 public class ThreadC extends Thread {

     private C c;

     public ThreadC(C c) {
         super();
         this.c = c;
     }

     @Override
     public void run() {
         while(true) {
             c.getValue();
         }
     }

 }

 package p_c_allWait;

 public class Run {

     public static void main(String[] args) {
         String lock = "";
         P p = new P(lock);
         C r = new C(lock);
         ThreadP[] pThread = new ThreadP[2];
         ThreadC[] cThread = new ThreadC[2];
         for(int i=0; i<2; i++) {
             pThread[i] = new ThreadP(p);
             pThread[i].setName("生产者 " + (i+1));
             cThread[i] = new ThreadC(r);
             cThread[i].setName("消费者 " + (i+1));
             pThread[i].start();
             cThread[i].start();
         }
     }

 }

notify每次只唤醒一个线程。

而notify唤醒线程是随机的，并不能保证每次唤醒的是异类线程，即生产者唤醒的可能是另一个生产者的线程。