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

下面例子用来做concurrentLinkedQueue和arrayList 加数据和减数据的性能比较

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 queue = new ConcurrentLinkedQueue();
		List list = new ArrayList();
		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 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