Java并发编程-Semaphore使用

﹏ヽ暗。殇╰゛Y 2021-11-16 05:58 308阅读 0赞

Java并发编程-Semaphore使用  
使用场景：Semaphore（信号量）同时运行多少个并发执行，比如我现在设置30个线程访问，可以通过Semaphore控制同时多个线程同时访问的，

代码如下：

public class SemaphoreTest {
        private static final int THREAD_COUNT = 30;
        private static final ExecutorService threadPool = Executors.newFixedThreadPool(THREAD_COUNT);//设置30个线程
        private static Semaphore semaphore = new Semaphore(10);//并发控制10个
    
        public static void main(String[] args) {
            for (int i = 0; i < THREAD_COUNT; i++) {
                threadPool.execute(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            semaphore.acquire();
                            TimeUnit.SECONDS.sleep(1);
                            System.out.println(Thread.currentThread().getName()+"---------");
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }finally {
                            semaphore.release();
                        }
                    }
                });
            }
            threadPool.shutdown();
        }
    }

pool-1-thread-1---------  
pool-1-thread-2---------  
pool-1-thread-3---------  
pool-1-thread-4---------  
pool-1-thread-5---------  
pool-1-thread-6---------  
pool-1-thread-7---------  
pool-1-thread-9---------  
pool-1-thread-8---------  
pool-1-thread-10---------  
pool-1-thread-13---------  
pool-1-thread-12---------  
pool-1-thread-11---------  
pool-1-thread-14---------  
pool-1-thread-17---------  
pool-1-thread-16---------  
pool-1-thread-15---------  
pool-1-thread-20---------  
pool-1-thread-19---------  
pool-1-thread-18---------  
pool-1-thread-21---------  
pool-1-thread-22---------  
pool-1-thread-23---------  
pool-1-thread-24---------  
pool-1-thread-25---------  
pool-1-thread-26---------  
pool-1-thread-27---------  
pool-1-thread-29---------  
pool-1-thread-28---------  
pool-1-thread-30---------  
运行结果分析：可以看到输出时，一次输出10个，一共输出3次。也就是每次只允许10个线程进入执行任务。