java多线程ReentrantLock、sync、ReentrantReadWriteLock性能比较

今天在了解ReentrantReadWriteLock的时候，看到了一篇文章，模拟了ReentrantLock、synchronized、ReentrantReadWriteLock三种锁在不同场景下的性能情况，对了解这三种锁在不同场景下的性能会有一定帮助。

代码：

import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

public class CurrentObject {

	private static Random random = new Random();

	public final static int READ_NUM = 180;// 读线程数

	public final static int WRITE_NUM = 20;// 写线程数

	private int value;//并发需要读写的值

	private ReadWriteLock lock = new ReentrantReadWriteLock();

	private Lock locknew = new ReentrantLock();
	
	/**
	 * 用于读/写平均耗时的展现
	 */
	public static void display() {
		System.out.println("读平均耗时:"
				+ (TimeCostUtils.getReadLong().get() / READ_NUM) + " ns");

		System.out.println("写平均耗时:"
				+ (TimeCostUtils.getWriteLong().get() / WRITE_NUM) + " ns");
	}
	
	/**
	 * 通过ReentrantReadWriteLock添加读锁
	 * @return value
	 * {@link ReentrantReadWriteLock}
	 */
	public int getValueLock() {
		lock.readLock().lock();
		try {
			return value;
		} finally {
			lock.readLock().unlock();
		}
	}
	
	/**
	 * 通过ReentrantReadWriteLock添加写锁
	 * @param value
	 */
	public void setValueLock(int value) {
		lock.writeLock().lock();
		try {
			this.value = value;
		} finally {
			lock.writeLock().unlock();
		}

	}
	
	/**
	 * 通过ReentrantLock添加读锁
	 * @return value
	 * {@link ReadWriteLock}
	 */
	public int getValueNew() {
		locknew.lock();
		try {
			return value;
		} finally {
			locknew.unlock();
		}
	}
	
	/**
	 * 通过ReentrantLock添加写锁
	 * @param value
	 */
	public void setValueNew(int value) {
		locknew.lock();
		try {
			this.value = value;
		} finally {
			locknew.unlock();
		}

	}

	/**
	 * 通过synchronized添加读锁
	 * @return value
	 */
	public synchronized int getValueSyn() {
		return value;
	}
	
	/**
	 * 通过synchronized添加写锁
	 * @param value
	 */
	public synchronized void setValueSyn(int value) {
		this.value = value;
	}
	
	/**
	 * 测试方法
	 * @param args
	 * @throws InterruptedException
	 */
	public static void main(String[] args) throws InterruptedException {

		//防止线程池大小过大，CPU过多的上下文切换导致的开销影响,线程池大小必须同总共开启的对象
		int maxProcessor = READ_NUM + WRITE_NUM;
		final ExecutorService newFixedThreadPool = Executors
				.newFixedThreadPool(maxProcessor);

		final CountDownLatch latch = new CountDownLatch(READ_NUM + WRITE_NUM);// 最后关闭线程池
		
		final CyclicBarrier barrier = new CyclicBarrier(READ_NUM + WRITE_NUM);// 等待所有线程启动后并发读写

		final CurrentObject concurrentObject = new CurrentObject();

		for (int i = 0; i < READ_NUM; i++) {
			newFixedThreadPool.execute(new Runnable() {
				@Override
				public void run() {
					try {
						barrier.await();
					} catch (Exception e) {
						e.printStackTrace();
					}

					TimeCostUtils.start(TimeCostUtils.READ);
					concurrentObject.getValueLock();
					TimeCostUtils.end();

					latch.countDown();
				}
			});
		}

		for (int i = 0; i < WRITE_NUM; i++) {
			newFixedThreadPool.execute(new Runnable() {

				@Override
				public void run() {

					int nextInt = random.nextInt(1000);
					try {
						barrier.await();
					} catch (Exception e) {
						e.printStackTrace();
					}

					TimeCostUtils.start(TimeCostUtils.WRITE);
					concurrentObject.setValueLock(nextInt);
					TimeCostUtils.end();

					latch.countDown();
				}
			});
		}

		latch.await();

		newFixedThreadPool.shutdown();

		// 系统退出前，关闭线程池及计算平均耗时、总耗时
		Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {

			@Override
			public void run() {

				display();
			}
		}));

	}

}

import java.util.concurrent.atomic.AtomicLong;

public class TimeCostUtils {
	private static AtomicLong readLong = new AtomicLong();

	private static AtomicLong writeLong = new AtomicLong();

	public final static String WRITE = "write";

	public final static String READ = "read";

	static ThreadLocal<TimesRecords> recordMap = new ThreadLocal<TimesRecords>();

	public static void start(String prefix) {

		TimesRecords timesRecords = new TimesRecords(prefix, System.nanoTime());
		recordMap.set(timesRecords);
	}

	public static void end() {
		TimesRecords timesRecords = recordMap.get();
		long cost = System.nanoTime() - timesRecords.getCost();

		// 计算每次的开销时间
		if (timesRecords.getName().equals(WRITE)) {
			writeLong.addAndGet(cost);
		} else {
			readLong.addAndGet(cost);
		}
	}

	public static AtomicLong getReadLong() {
		return readLong;
	}

	public static AtomicLong getWriteLong() {
		return writeLong;
	}

	static class TimesRecords {

		private String name;

		private long cost;

		public TimesRecords(String name, long cost) {
			this.name = name;
			this.cost = cost;
		}

		public String getName() {
			return name;
		}

		public void setName(String name) {
			this.name = name;
		}

		public long getCost() {
			return cost;
		}

		public void setCost(long cost) {
			this.cost = cost;
		}

	}
}

测试数据：

原文：http://www.inter12.org/archives/292

由最代码官方编辑于2016-9-23 10:26:37