线程问题--（Semaphore计数线程不安全）

快来打我* 2022-05-22 11:07 162阅读 0赞

package com.mmall.concurrency;  
  
  
import com.mmall.concurrency.annoations.NotThreadSafe;  
  
  
import java.util.concurrent.CountDownLatch;  
import java.util.concurrent.ExecutorService;  
import java.util.concurrent.Executors;  
import java.util.concurrent.Semaphore;  
  
  
/\*\*  
 \* 模拟并发    这里请求总数 5000     执行结果达不到5000  
 \* @author 81046  
 \*  
 \*/  
@NotThreadSafe  
public class ConcurrencyTest \{  
  
  
    // 请求总数  
    public static int clientTotal = 5000;  
  
  
    // 同时并发执行的线程数  
    public static int threadTotal = 200;  
  
  
    public static int count = 0;  
  
  
    public static void main(String\[\] args) throws Exception \{  
        ExecutorService executorService = Executors.newCachedThreadPool();  
        final Semaphore semaphore = new Semaphore(threadTotal);  
        final CountDownLatch countDownLatch = new CountDownLatch(clientTotal);  
        for (int i = 0; i < clientTotal ; i++) \{  
            executorService.execute(() -> \{  
                try \{  
                    semaphore.acquire();  
                    add();  
                    semaphore.release();  
                \} catch (Exception e) \{  
                System.out.println("exception"+ e);  
                \}  
                countDownLatch.countDown();  
            \});  
        \}  
        countDownLatch.await();  
        executorService.shutdown();  
        System.out.println("count:\{\}"+ count);  
    \}  
  
  
    private static void add() \{  
        count++;  
    \}  
\}