ReentrantLock 大访问量同步问题

gibby 2014-11-05 10:06:49
写了一段代码 在大访问量时不能保持 synchronized 的一个接一个效果 求解答
下面是JAVA代码


	@Override

	public Map kill() {

		ReentrantLock lock = new ReentrantLock(); 

		Transaction tx =null;

		Jedis jedis =null;

		Map resultMap = new HashMap();

		try {

			lock.lock();

			System.out.println("thread name : "+Thread.currentThread().getName() +" work ");

			jedis = RedisApi.getResource();

			Good skGood = (Good)RedisApi.get(CommonDefinition.SEC_KILL_GOOD.getBytes());

			int secQuantity = skGood.getSecQuantity();

			if(secQuantity<=0){

				resultMap.put("scuess", false);

			}else{

				tx = jedis.multi();

				skGood.setSecQuantity(secQuantity-1);

				RedisApi.set(CommonDefinition.SEC_KILL_GOOD, skGood);

				tx.exec();

				resultMap.put("scuess", true);

				resultMap.put("kill_good_num", secQuantity);

			}

			//System.out.println(resultMap.get("kill_good_num")+"/ "+lock.getHoldCount()+" / "+lock.toString());

			return resultMap;

		} catch (Exception e) {

			e.printStackTrace();

			if(null!=tx){

				tx.discard();

			}

			RedisApi.returnBrokenResource(jedis);

		}finally{

			RedisApi.returnResource(jedis);

			lock.unlock();

			System.out.println("thread name : "+Thread.currentThread().getName() +" finished ");

		}

		return null;

	}


使用synchronized 50个线程访问的结果


thread name : http-bio-8080-exec-5 work 

thread name : http-bio-8080-exec-5 finished 

thread name : http-bio-8080-exec-7 work 

thread name : http-bio-8080-exec-7 finished 

thread name : http-bio-8080-exec-6 work 

thread name : http-bio-8080-exec-6 finished 

thread name : http-bio-8080-exec-3 work 

thread name : http-bio-8080-exec-3 finished 

thread name : http-bio-8080-exec-4 work 

thread name : http-bio-8080-exec-4 finished 

thread name : http-bio-8080-exec-9 work 

thread name : http-bio-8080-exec-9 finished 

thread name : http-bio-8080-exec-8 work 

thread name : http-bio-8080-exec-8 finished 

thread name : http-bio-8080-exec-10 work 

thread name : http-bio-8080-exec-10 finished 

thread name : http-bio-8080-exec-11 work 

thread name : http-bio-8080-exec-11 finished 

thread name : http-bio-8080-exec-12 work 

thread name : http-bio-8080-exec-12 finished 

thread name : http-bio-8080-exec-13 work 

thread name : http-bio-8080-exec-13 finished 

thread name : http-bio-8080-exec-14 work 

thread name : http-bio-8080-exec-14 finished 

thread name : http-bio-8080-exec-15 work 

thread name : http-bio-8080-exec-15 finished 

thread name : http-bio-8080-exec-16 work 

thread name : http-bio-8080-exec-16 finished 

thread name : http-bio-8080-exec-17 work 

thread name : http-bio-8080-exec-17 finished 

thread name : http-bio-8080-exec-19 work 

thread name : http-bio-8080-exec-19 finished 

thread name : http-bio-8080-exec-18 work 

thread name : http-bio-8080-exec-18 finished 

thread name : http-bio-8080-exec-20 work 

thread name : http-bio-8080-exec-20 finished 

thread name : http-bio-8080-exec-32 work 

thread name : http-bio-8080-exec-32 finished 

thread name : http-bio-8080-exec-8 work 

thread name : http-bio-8080-exec-8 finished 

thread name : http-bio-8080-exec-6 work 

thread name : http-bio-8080-exec-6 finished 

thread name : http-bio-8080-exec-4 work 

thread name : http-bio-8080-exec-4 finished 

thread name : http-bio-8080-exec-5 work 

thread name : http-bio-8080-exec-5 finished 

thread name : http-bio-8080-exec-19 work 

thread name : http-bio-8080-exec-19 finished 

thread name : http-bio-8080-exec-9 work 

thread name : http-bio-8080-exec-9 finished 

thread name : http-bio-8080-exec-5 work 

thread name : http-bio-8080-exec-5 finished 

thread name : http-bio-8080-exec-31 work 

thread name : http-bio-8080-exec-31 finished 

thread name : http-bio-8080-exec-3 work 

thread name : http-bio-8080-exec-3 finished 

thread name : http-bio-8080-exec-4 work 

thread name : http-bio-8080-exec-4 finished 

thread name : http-bio-8080-exec-14 work 

thread name : http-bio-8080-exec-14 finished 

thread name : http-bio-8080-exec-20 work 

thread name : http-bio-8080-exec-20 finished 

thread name : http-bio-8080-exec-10 work 

thread name : http-bio-8080-exec-10 finished 

thread name : http-bio-8080-exec-19 work 

thread name : http-bio-8080-exec-19 finished 

thread name : http-bio-8080-exec-21 work 

thread name : http-bio-8080-exec-21 finished 

thread name : http-bio-8080-exec-30 work 

thread name : http-bio-8080-exec-30 finished 

thread name : http-bio-8080-exec-12 work 

thread name : http-bio-8080-exec-12 finished 

thread name : http-bio-8080-exec-26 work 

thread name : http-bio-8080-exec-26 finished 

thread name : http-bio-8080-exec-22 work 

thread name : http-bio-8080-exec-22 finished 

thread name : http-bio-8080-exec-23 work 

thread name : http-bio-8080-exec-23 finished 

thread name : http-bio-8080-exec-13 work 

thread name : http-bio-8080-exec-13 finished 

thread name : http-bio-8080-exec-28 work 

thread name : http-bio-8080-exec-28 finished 

thread name : http-bio-8080-exec-5 work 

thread name : http-bio-8080-exec-5 finished 

thread name : http-bio-8080-exec-8 work 

thread name : http-bio-8080-exec-8 finished 

thread name : http-bio-8080-exec-3 work 

thread name : http-bio-8080-exec-3 finished 

thread name : http-bio-8080-exec-18 work 

thread name : http-bio-8080-exec-18 finished 

thread name : http-bio-8080-exec-14 work 

thread name : http-bio-8080-exec-14 finished 

thread name : http-bio-8080-exec-20 work 

thread name : http-bio-8080-exec-20 finished 

thread name : http-bio-8080-exec-10 work 

thread name : http-bio-8080-exec-10 finished 

thread name : http-bio-8080-exec-19 work 

thread name : http-bio-8080-exec-19 finished 

thread name : http-bio-8080-exec-21 work 

thread name : http-bio-8080-exec-21 finished


以下是用上面的ReentrantLock 50个线程访问的效果


thread name : http-bio-8080-exec-4 work 

thread name : http-bio-8080-exec-5 work 

thread name : http-bio-8080-exec-3 work 

thread name : http-bio-8080-exec-6 work 

thread name : http-bio-8080-exec-7 work 

thread name : http-bio-8080-exec-4 finished 

thread name : http-bio-8080-exec-6 finished 

thread name : http-bio-8080-exec-5 finished 

thread name : http-bio-8080-exec-3 finished 

thread name : http-bio-8080-exec-7 finished 

thread name : http-bio-8080-exec-9 work 

thread name : http-bio-8080-exec-8 work 

thread name : http-bio-8080-exec-9 finished 

thread name : http-bio-8080-exec-8 finished 

thread name : http-bio-8080-exec-10 work 

thread name : http-bio-8080-exec-10 finished 

thread name : http-bio-8080-exec-1 work 

thread name : http-bio-8080-exec-1 finished 

thread name : http-bio-8080-exec-11 work 

thread name : http-bio-8080-exec-11 finished 

thread name : http-bio-8080-exec-12 work 

thread name : http-bio-8080-exec-12 finished 

thread name : http-bio-8080-exec-13 work 

thread name : http-bio-8080-exec-13 finished 

thread name : http-bio-8080-exec-14 work 

thread name : http-bio-8080-exec-14 finished 

thread name : http-bio-8080-exec-16 work 

thread name : http-bio-8080-exec-16 finished 

thread name : http-bio-8080-exec-15 work 

thread name : http-bio-8080-exec-15 finished 

thread name : http-bio-8080-exec-14 work 

thread name : http-bio-8080-exec-14 finished 

thread name : http-bio-8080-exec-2 work 

thread name : http-bio-8080-exec-2 finished 

thread name : http-bio-8080-exec-24 work 

thread name : http-bio-8080-exec-24 finished 

thread name : http-bio-8080-exec-7 work 

thread name : http-bio-8080-exec-11 work 

thread name : http-bio-8080-exec-7 finished 

thread name : http-bio-8080-exec-11 finished 

thread name : http-bio-8080-exec-19 work 

thread name : http-bio-8080-exec-19 finished 

thread name : http-bio-8080-exec-4 work 

thread name : http-bio-8080-exec-4 finished 

thread name : http-bio-8080-exec-11 work 

thread name : http-bio-8080-exec-11 finished 

thread name : http-bio-8080-exec-15 work 

thread name : http-bio-8080-exec-15 finished 

thread name : http-bio-8080-exec-3 work 

thread name : http-bio-8080-exec-3 finished 

thread name : http-bio-8080-exec-7 work 

thread name : http-bio-8080-exec-7 finished 

thread name : http-bio-8080-exec-18 work 

thread name : http-bio-8080-exec-18 finished 

thread name : http-bio-8080-exec-18 work 

thread name : http-bio-8080-exec-18 finished 

thread name : http-bio-8080-exec-1 work 

thread name : http-bio-8080-exec-1 finished 

thread name : http-bio-8080-exec-17 work 

thread name : http-bio-8080-exec-17 finished 

thread name : http-bio-8080-exec-25 work 

thread name : http-bio-8080-exec-25 finished 

thread name : http-bio-8080-exec-2 work 

thread name : http-bio-8080-exec-2 finished 

thread name : http-bio-8080-exec-7 work 

thread name : http-bio-8080-exec-7 finished 

thread name : http-bio-8080-exec-23 work 

thread name : http-bio-8080-exec-23 finished 

thread name : http-bio-8080-exec-13 work 

thread name : http-bio-8080-exec-13 finished 

thread name : http-bio-8080-exec-19 work 

thread name : http-bio-8080-exec-19 finished 

thread name : http-bio-8080-exec-12 work 

thread name : http-bio-8080-exec-12 finished 

thread name : http-bio-8080-exec-6 work 

thread name : http-bio-8080-exec-6 finished 

thread name : http-bio-8080-exec-4 work 

thread name : http-bio-8080-exec-4 finished 

thread name : http-bio-8080-exec-21 work 

thread name : http-bio-8080-exec-21 finished 

thread name : http-bio-8080-exec-18 work 

thread name : http-bio-8080-exec-18 finished 

thread name : http-bio-8080-exec-1 work 

thread name : http-bio-8080-exec-1 finished 

thread name : http-bio-8080-exec-17 work 

thread name : http-bio-8080-exec-17 finished 

......

如果想要用lock 实现按顺序的一个接一个完成要如果写 求解答
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gibby 2014-11-18
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我看了文档说 lock方法就是阻塞的了跟同步关键字一样
gibby 2014-11-18
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我看了文档说 lock方法就是阻塞的了跟同步关键字一样
晓风吹雾 2014-11-05
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ReentrantLock 是重入所， lock 后其他的线程 还是会进入，一般配合condition, 重入所一般为了提高效率，是其他的线程不会呆呆的block，而是 有更多的选择余地。 你要做成纯粹的窜行执行，为什不用 synchronized 一般 ReentrantLock 配合 condition 下面是配合 condition，模仿synchronized窜行执行的效果。 这样没什么意义 

package jp.co.nec.aim.demo.servlet;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

public class Entrance {

	private static final ReentrantLock lock = new ReentrantLock(false);
	private static final Condition c = lock.newCondition();

	public static void main(String[] args) {
		lock.lock();
		try {
			c.await();
			// do something
			System.out.print(11);
			c.notify();
		} catch (InterruptedException e) {
		} finally {
			lock.unlock();
		}
	}
}
gibby 2014-11-05
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引用 2 楼 zhouren1314 的回复:
加上 一个 boolean变量试试，每次操作时判断一下，只是思路，不知道能行么？
判断什么？
乔不思 2014-11-05
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加上 一个 boolean变量试试，每次操作时判断一下，只是思路，不知道能行么？
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