Java并发编程之生产者消费者模式

有关Java多线程，前面我记录自己对于线程池创建的两种方式，以及线程池如何创建线程（这里自己在加深一下印象：当执行execute方法时候，会将任务放入addWorker方法中，addWorker将任务放入到Worker构造器中，该类中runWorker方法有一个getTask方法，这个方法中有一段代码：boolean timed = allowCoreThreadTimeOut || wc > corePoolSize; Runnable r = timed ? workQueue.poll(keepAliveTime, TimeUnit.NANOSECONDS) : workQueue.take();会从队列中取出任务执行，否则take()核心线程进行阻塞，保证核心线程不被销毁）

在多线程并发任务中，很多并发问题是由于对于JVM中主内存（主要包括方法区和堆，有关JVM知识可以自行查阅）中共享变量的不安全操作。所以我觉得就扯出来锁，目前我所知道的就是乐观锁/悲观锁,公平锁/非公平锁，互斥锁/读写锁（ReentrantLock/ReadWriteLock）以及自旋锁，分段锁（concurrentHashMap）。这些锁在不同场景的应用能够解决不同的并发问题。我又想扯到AQS中，但是我理解还很肤浅，不在叙述，开始实现生产者消费者模式：

我这里用两种方法去实现：

一种是利用BlockingQueue,一种是利用Condition（多线程间协调通信工具类）的await、signalAll

package com.elastic.search.ProCus;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ProCus {
    public static void main(String[] args) {
        //new ProCus().BloQueueTest(); // BlockingQueue
        new ProCus().ConditionTest(); // await signalAll
    }

    public void BloQueueTest() {
        Queue queue = new Queue();
        new Thread(new Producer(queue), "pro1").start();

        new Thread(new Customer(queue), "c1").start();
        new Thread(new Customer(queue), "c2").start();
        new Thread(new Customer(queue), "c3").start();
    }

    public void ConditionTest() {
        Lock lock = new ReentrantLock();
        Condition producer = lock.newCondition();
        Condition customer = lock.newCondition();
        Cache cache = new Cache(lock, producer, customer);
        new Thread(new Produce2(cache), "p1").start();

        new Thread(new Customer2(cache), "c1").start();
        new Thread(new Customer2(cache), "c2").start();
    }
}

class Queue {
    private BlockingQueue blockingQueue = new LinkedBlockingQueue(10);

    public void Producer() {
        try {
            blockingQueue.put(1);
            System.out.println(Thread.currentThread().getName() + "生产，当前资源数：" + blockingQueue.size());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    public void customer() {
        try {
            System.out.println(Thread.currentThread().getName() + "进入到队列中准备消耗资源，此时资源池数量:" + blockingQueue.size());
            blockingQueue.take();
            System.out.println(Thread.currentThread().getName() + "消耗，当前资源数：" + blockingQueue.size());
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

class Producer implements Runnable {
    private Queue queue;

    public Producer(Queue queue) {
        this.queue = queue;
    }

    @Override
    public void run() {
        for (; ; ) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            queue.Producer();
        }
    }
}

class Customer implements Runnable {
    private Queue queue;

    public Customer(Queue queue) {
        this.queue = queue;
    }

    @Override
    public void run() {
        for (; ; ) {
            try {
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            queue.customer();
        }
    }
}

class Cache {
    int size = 10;
    int num = 0;
    private Lock lock;
    private Condition proCondition;
    private Condition cusCondition;

    Cache(Lock lock, Condition proCondition, Condition cusCondition) {
        this.lock = lock;
        this.cusCondition = cusCondition;
        this.proCondition = proCondition;
    }

    public void producer() {
        lock.lock();
        try {
            if (size > num) {
                num++;
                System.out.println(Thread.currentThread().getName() + "product,num:" + num);
                cusCondition.signalAll();
            } else {
                try {
                    System.out.println("size > num pro await");
                    proCondition.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        } finally {
            lock.unlock();
        }
    }

    public void customer() {
        lock.lock();
        try {
            if (num > 0) {
                num--;
                System.out.println(Thread.currentThread().getName() + "customer,num:" + num);
                proCondition.signalAll();
            } else {
                try {
                    System.out.println(" num  < 0 cus await");
                    cusCondition.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        } finally {
            lock.unlock();
        }
    }
}

class Produce2 implements Runnable {
    private Cache cache;

    Produce2(Cache cache) {
        this.cache = cache;
    }

    @Override
    public void run() {
        for (; ; ) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            cache.producer();
        }
    }
}

class Customer2 implements Runnable {
    private Cache cache;

    Customer2(Cache cache) {
        this.cache = cache;
    }

    @Override
    public void run() {
        for (; ; ) {
            try {
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            cache.customer();
        }
    }
}

Java并发编程之生产者消费者模式

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