Semaphore 信号量
作者:互联网
一、获取单个许可
信号量设置为3,每次获取1个许可,那么就可以连续获得3个许可。
如下面的信号量Demo
@Slf4j public class SemaphoreExample1 { private static int threadCount = 20; public static void main(String[] args) throws InterruptedException { ExecutorService exec = Executors.newCachedThreadPool(); final Semaphore semaphore = new Semaphore(3); for(int i = 0; i < threadCount; i++){ final int threadNum = i; exec.execute(()->{ try { semaphore.acquire();//获得一个许可 test(threadNum); semaphore.release();//释放一个许可 } catch (InterruptedException e) { e.printStackTrace(); } }); } exec.shutdown(); } private static void test(int threadNum) throws InterruptedException { log.info("{}", threadNum); Thread.sleep(1000); } }
打印结果如下。信号量设置为3。 差不多每隔1秒钟打印3条数据。
二、获得多个许可
线程数为20,信号量为3,每次获得3个许可。相当于单线程。
@Slf4j public class SemaphoreExample2 { private static int threadCount = 20; public static void main(String[] args) throws InterruptedException { ExecutorService exec = Executors.newCachedThreadPool(); final Semaphore semaphore = new Semaphore(3); for(int i = 0; i < threadCount; i++){ final int threadNum = i; exec.execute(()->{ try { semaphore.acquire(3);//获得3个许可, 信号量为3,相当于单线程执行 test(threadNum); semaphore.release(3);//释放3个许可 } catch (InterruptedException e) { e.printStackTrace(); } }); } exec.shutdown(); } private static void test(int threadNum) throws InterruptedException { log.info("{}", threadNum); Thread.sleep(1000); } }
标签:许可,int,InterruptedException,信号量,static,Semaphore,threadNum 来源: https://www.cnblogs.com/linlf03/p/12748093.html