java并发深入

测试表明上述对于300个线程，每个线程做10000次加１操作，内置锁syncronized比atomicInteger效率要高

测试代码如下：

public class SyncWithAtomicTest {
	
	private int count=0;
	
	private static final int threadCount=300;
	
	private static final int countNum=10000;
	
	private final AtomicInteger countAtomicInteger=new AtomicInteger(0);

	private static final ExecutorService threadPool=Executors.newFixedThreadPool(threadCount);
	
	private final CountDownLatch latchStart=new CountDownLatch(threadCount);
	
	private final CountDownLatch latchEnd=new CountDownLatch(threadCount);
	
	public synchronized void addWithCountSync(){
		for(int i=0;i<countNum;i++){
			count++;
		}
	}
	
	public void addWithAtomicCount(){
		for(int i=0;i<countNum;i++){
			countAtomicInteger.incrementAndGet();
		}
	}
	
	public static void main(String[] args) throws InterruptedException {
		
		SyncWithAtomicTest obj=new SyncWithAtomicTest();
		
		Long oldTime=System.currentTimeMillis();
		
		for(int i=0;i<threadCount;i++){
			CountTask t=new CountTask();
			t.setTarget(obj);
			
			threadPool.execute(t);
		}
		
		obj.latchEnd.await();
		
		Long endTime=System.currentTimeMillis()-oldTime;
		
//		System.out.println("===============atomic all finish,cost:"+endTime+",the res:"+obj.countAtomicInteger.get());
		
		System.out.println("===============sync all finish,cost:"+endTime+",the res:"+obj.count);
	}
	
	static class CountTask implements Runnable{
		private SyncWithAtomicTest target;

		public void run() {
			try {
				target.latchStart.countDown();
				target.latchStart.await();
				
				//we do add oper when all threads is ready 
				target.addWithCountSync();
				
//				target.addWithAtomicCount();
				
				System.out.println("thread:"+Thread.currentThread().getId()+",finish the work");
				
				target.latchEnd.countDown();
				
				
			} catch (InterruptedException e) {
				e.printStackTrace();
				Thread.currentThread().interrupt();
			}
		}

		public void setTarget(SyncWithAtomicTest target) {
			this.target = target;
		}
	}

}

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java并发深入

原文：http://blog.csdn.net/zhaozhenzuo/article/details/36622351