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。