java-并发集合-并发hash表 ConcurrentHashMap 演示

java-并发集合-并发hash表 ConcurrentHashMap 演示

package me.grass.demo.concurrent;import java.util.Date;import java.util.concurrent.ConcurrentLinkedQueue;import java.util.concurrent.CountDownLatch;import java.util.concurrent.Executors;/** * 并发集合 java.util.concurrent.ConcurrentHashMap 演示* 并发 10 个生产者产生数据，并发  5  个消费消费数据；调整活动线程数将减小处理时间* @author xxj  */public class ConcurrentHashMapDemo {/** * 生产者快，消费者慢 * @param args * @throws InterruptedException *  @author xxj  */public static void main(String[] args) throws InterruptedException {Date before=new Date();int pTotalThread =100; //最大线程数（生产者）int pActivities=10; //最大线程数（生产者）int cTotalThread =50; //活动线程数（消费者）int cActivities=5; //活动线程数（消费者）_lCountDownLatch = new CountDownLatch(pTotalThread+cTotalThread);initKeys(pTotalThread);startProducer(pActivities,pTotalThread);startConsumer(cActivities,cTotalThread);_lCountDownLatch.await();//等待所有线程完成Date after = new Date();System.out.println("队列为空："+_concurrentHashMap.isEmpty());System.out.println("耗时："+((after.getTime()-before.getTime())/1000));System.out.println("同步队列："+_lCountDownLatch.getCount());}private static java.util.concurrent.CountDownLatch _lCountDownLatch;private static java.util.concurrent.ConcurrentHashMap<Integer,Integer> _concurrentHashMap = new java.util.concurrent.ConcurrentHashMap<Integer,Integer>();private static java.util.concurrent.ConcurrentLinkedQueue<Integer> _keys =new ConcurrentLinkedQueue<Integer>();private static void initKeys(int size){for(int i=0;i<size;i++){_keys.add(i);}}private static void startProducer(int active,int totalThread) throws InterruptedException{java.util.concurrent.ExecutorService pool = Executors.newFixedThreadPool(active);int size =1024*1024*10;//产生 3 M 数据Thread thread ;for(int i=0;i<totalThread;i++){thread = new Thread(new producer(i,size));pool.execute(thread);}}private static void startConsumer(int active,int totalThread) throws InterruptedException{java.util.concurrent.ExecutorService pool = Executors.newFixedThreadPool(active);Thread thread ;//启动x个消费者for(int i=0;i<totalThread;i++){thread = new Thread(new consumer());pool.execute(thread);}}/** * 生产者 * @author xxj  * */private static class producer implements Runnable{public producer(int key,int size){_size=size;_key=key;}int _key;int _size;public void run() {ConcurrentHashMapDemo._concurrentHashMap.put(_key,_key);//生产System.out.println("已创建："+_key);ConcurrentHashMapDemo._lCountDownLatch.countDown();//线程同步递减try {Thread.sleep(500);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}/** * 消费者 * @author xxj  * */private static class consumer implements Runnable{public consumer(){}public void run() {Integer key = 0;Integer nInteger=null;//循环消费，直到队列内容为空while(!ConcurrentHashMapDemo._concurrentHashMap.isEmpty() &&!ConcurrentHashMapDemo._keys.isEmpty()){key =  ConcurrentHashMapDemo._keys.poll();//获取 keyif(ConcurrentHashMapDemo._concurrentHashMap.containsKey(key)){nInteger = ConcurrentHashMapDemo._concurrentHashMap.get(key);//消费}System.err.println("消费："+nInteger);try {Thread.sleep(500);//每次消费等一会儿} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}}ConcurrentHashMapDemo._lCountDownLatch.countDown();//线程同步递减}}}