Semaphore
- Semaphore(信号量)是用来控制同时访问特定资源的线程数量，它通过协调各个线程，以保证合理的使用公共资源
- 不要将SemaPhore和服务限流关联起来
- Semaphore控制访问资源的并发数，而RateLimiter控制访问资源的速度。
样例代码
public class SemaphoreTest {
@Test
public void test1() {
final int THREAD_COUNT = 30;
ExecutorService executorService = Executors.newFixedThreadPool(THREAD_COUNT);
final Semaphore s = new Semaphore(10);
final CountDownLatch countDownLatch = new CountDownLatch(THREAD_COUNT);
long startTime = System.currentTimeMillis();
for( int i = 0; i < THREAD_COUNT; i++) {
executorService.submit(new Runnable() {
@Override
public void run() {
try {
s.acquire();
System.out.println("save data");
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//设置日期格式
System.out.println(df.format(new Date()));// new Date()为获取当前系统时间
Thread.sleep(1000);
countDownLatch.countDown();
} catch (InterruptedException e) {
} finally {
s.release();
}
}
});
}
try {
countDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}
long endTime = System.currentTimeMillis();
System.out.println(endTime - startTime);
executorService.shutdown();
}
}
