多线程学习笔记十——使用ConcurrentLinkedQueue代替ArrayList

package day4;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class ConcurrentLinkedQueueDemo {
    public static void main(String[] args) {
        ConcurrentLinkedQueue<String> queue = new ConcurrentLinkedQueue<String>();
        List<String> list = new ArrayList<String>();
        ExecutorService executor = Executors.newFixedThreadPool(16);
        ExecutorService executor2 = Executors.newFixedThreadPool(16);
        long start = System.currentTimeMillis();
        for (int i = 0; i < 100000; i++) {
            executor.execute(new Thread(""+i){
                public void run() {
                    queue.offer("value" + Thread.currentThread().getName());
                }
            });
        }
        for (int i = 0; i < 100000; i++) {
            executor.execute(new Thread(""+i){
                public void run() {
                    while(!queue.isEmpty()) {
                        queue.poll();
                    }
                }
            });
        }
        executor.shutdown();
        System.out.println("ConcurrentLinkedQueue: "+(System.currentTimeMillis()-start));
        long start2 = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
            executor2.execute(new Thread(""+i){
                public void run() {
                    synchronized (list) {
                        list.add("value" + Thread.currentThread().getName());
                    }
                }
            });
        }
        for (int i = 0; i < 100000; i++) {
            executor2.execute(new Thread(""+i){
                public void run() {
                    for(Iterator<String> ite = list.iterator();ite.hasNext();) {
                        ite.next();
                    }
                }
            });
        }
        executor2.shutdown();
        System.out.println("ArrayList: "+(System.currentTimeMillis()-start2));
    }
}

console输出：

ConcurrentLinkedQueue: 348
ArrayList: 1331

注意：不要使用queue.size()来判断队列是否为空，因为此方法会遍历整个ConcurrentLinkedQueue