Semaphore

 

import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

public class SemaphoreTest {

	//If a factory has 5 machines, but there are 8 workers, a machine can only be used by one worker at the same time, only when it is used up,
	//Other workers can continue to use. Then we can do it through Semaphore
	 public static void main(String[] args) {
		 ExecutorService newFixedThreadPool = Executors.newFixedThreadPool(10);
		 int num = 5 ;
		 long start = System.currentTimeMillis();
		 Semaphore semaphore = new Semaphore(num);
		 for (int i = 0; i < 8; i++) {
			newFixedThreadPool.submit(new SemaphoreRunnable(semaphore));
		}
		 long end = System.currentTimeMillis();
		 newFixedThreadPool.shutdown();
		 
	 }

	 
	 public static class SemaphoreRunnable implements Runnable{
		private  Semaphore semaphore;
		 
		public SemaphoreRunnable(Semaphore semaphore) {
			this.semaphore = semaphore;
		}

		@Override
		public void run() {
			try {
				 long start = System.currentTimeMillis();
				 semaphore.acquire();
				 //Do some Thing
				 
				 Thread.sleep(1000);
				 semaphore.release();
				 long end = System.currentTimeMillis();
				 System.out.println(System.currentTimeMillis() +"=========" + (end-start)/1000);
			} catch (InterruptedException e) {
				e.printStackTrace ();
			}
		}
		 
	 }
}

 

 

 

 

 

 

 

 

 

 

 

 

 

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