高并发计数器

package day01.synchronize;

/**

• @title: Counter
• @description:
• @author: 北京小桔汇金网络科技有限公司
• @date: 2018/5/2 13:35 */ import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicInteger;

/**

• 关于count++在多线程调用状况下

• @author jan / public class Counter { // private volatile int count = 0; private AtomicInteger count = new AtomicInteger(1); /*

  • 为了保证数据的准确性，多线程的状况下须要加上synchronized关键字</br>
  • 不然会出现出乎预料的结果 这也是线程安全的重要体现 */ public void increment() { count.incrementAndGet(); }

  private int getCount() { return count.get(); }

  /**

  • 这里模拟一个递增的任务，递增目标为100W */ public static void main(String[] args) throws InterruptedException { final Counter counter = new Counter(); // final AtomicCounter counter = new AtomicCounter(); int workCount = 1000000; ExecutorService executor = Executors.newFixedThreadPool(10); long start = System.currentTimeMillis(); for (int i = 0; i < workCount; i++) { Runnable runnable = new Runnable() { @Override public void run() { counter.increment(); } }; executor.execute(runnable); } // 关闭启动线程，执行未完成的任务 executor.shutdown(); // 等待全部线程完成任务，完成后才继续执行下一步 executor.awaitTermination(Long.MAX_VALUE, TimeUnit.DAYS); System.out.println("耗时：" + (System.currentTimeMillis() - start) + "ms"); System.out.println("执行结果：count=" + counter.getCount()); } }