LongAdder和AtomicLong性能对比

Posted 2021-02-13 itbac

jdk1.8中新原子操作封装类LongAdder和jdk1.5的AtomicLong和synchronized的性能对比，直接上代码：

package com.itbac.cas;

import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.LongAdder;

// 测试用例： 同时运行2秒，检查谁的次数最多
public class LongAdderDemo {
    // synchronized 方式
    private long count = 0;
    // Atomic方式
    private AtomicLong acount = new AtomicLong(0L);
    // LongAdder 方式  （jdk1.8,新计数器）
    private LongAdder lacount = new LongAdder();

    // 运行时间，毫秒数
    private  int time=2000;

    // 同步代码块的方式
    public void testSync() throws InterruptedException {
        for (int i = 0; i < 3; i++) {
            new Thread(() -> {
                long starttime = System.currentTimeMillis();
                while (System.currentTimeMillis() - starttime < time) { // 运行两秒
                    synchronized (this) {
                        ++count;
                    }
                }
                long endtime = System.currentTimeMillis();
                System.out.println("SyncThread spend:" + (endtime - starttime) + "ms" + " v:" + count);
            }).start();
        }
    }



    public void testAtomic() throws InterruptedException {
        for (int i = 0; i < 3; i++) {
            new Thread(() -> {
                long starttime = System.currentTimeMillis();
                while (System.currentTimeMillis() - starttime < time) { // 运行两秒
                    acount.incrementAndGet(); // acount++;
                }
                long endtime = System.currentTimeMillis();
                System.out.println("AtomicThread spend:" + (endtime - starttime) + "ms" + " v:" + acount.incrementAndGet());
            }).start();
        }
    }


    public void testLongAdder() throws InterruptedException {
        for (int i = 0; i < 3; i++) {
            new Thread(() -> {
                long starttime = System.currentTimeMillis();
                while (System.currentTimeMillis() - starttime < time) { // 运行两秒
                    lacount.increment();
                }
                long endtime = System.currentTimeMillis();
                System.out.println("LongAdderThread spend:" + (endtime - starttime) + "ms" + " v:" + lacount.sum());
            }).start();
        }
    }

    public static void main(String[] args) throws InterruptedException {
        LongAdderDemo demo = new LongAdderDemo();
        demo.testSync();
        demo.testAtomic();
        demo.testLongAdder();
    }
}

看看输出结果：

SyncThread spend:2000ms v:25458554
SyncThread spend:2000ms v:25458554
SyncThread spend:2000ms v:25458554
AtomicThread spend:2000ms v:78489760
AtomicThread spend:2000ms v:78489759
AtomicThread spend:2000ms v:78489758
LongAdderThread spend:2000ms v:141154988
LongAdderThread spend:2000ms v:141154988
LongAdderThread spend:2000ms v:141352859

jdk版本,作者及类名：

* @since 1.5
* @author Doug Lea 
AtomicLong

* @since 1.8
* @author Doug Lea
LongAdder

让我们来膜拜一下大神！2秒破亿次累加。翻倍的性能提升。