今天测试了多线程并发计数的性能：结果测试性能为：

测试结果显示原子操作性能还是比较的差；

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;

public class Counter {
 
	private AtomicInteger atomicI = new AtomicInteger(0);
	ReentrantLock lock = new ReentrantLock();
	private int m = 0;
	private  int k = 0;
	private  int l = 0;
	public static void main(String[] args) {
		atomic(1);
		atomic(2);
		atomic(3);
		atomic(4);
	}
	
	public static void atomic(final int type){
		final Counter cas = new Counter();
		List<Thread> ts = new ArrayList<Thread>(600);
		long start = System.currentTimeMillis();
		for (int j = 0; j < 10000; j++) {
			Thread t = new Thread(new Runnable() {
				@Override
				public void run() {
					for (int i = 0; i < 1000; i++) {
						//cas.count();
						if(type==1){
							cas.safeCount();
						}else if(type==2){
							cas.count2();
						}else if(type==3){
							cas.count();
						}else if(type==4){
							cas.count1();
						}
					
						//cas.count1();
					}
				}
			});
			ts.add(t);
		}

		for (Thread t : ts) {
			
			t.start();
		}
		// 等待所有线程执行完成
		for (Thread t : ts) {
			try {
				t.join();
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}
		if(type==1){
			System.out.println(type +"automic操作"+cas.atomicI.get());
		}else if(type==2){
			System.out.println(type +"lock:操作"+cas.m);
		}else if(type==3){
			System.out.println(type +"synchronized:操作"+cas.k);
		}else if(type==4){
			System.out.println(type +"none:操作"+cas.l);
		}
	 
	
		
	
		System.out.println(System.currentTimeMillis() - start);
	}

	 
	/**
	 * 使用CAS实现线程安全计数器
	 */
	private void safeCount() {
		 
		 atomicI.incrementAndGet();
			 
	}
	/**
	 * 非线程安全计数器 存在竞争争条件，所以计算有错误 
	 */
	private void count1() {
		
		l++;
		 
	}
	/**
	 * 同步线程安全计数器
	 */
	private synchronized void count() {
	 
		k++;
	 
	}
	/**
	 * 锁线程安全计数器
	 */
	private void count2() {
		//如果不加锁会计算出问题
		lock.lock();
		try{
		m++;
		}catch(Exception e ){
			
		}finally{
			lock.unlock();
		}
	}
}