控制能同時有幾個線程並發Semaphore
阿新 • • 發佈：2018-08-24
ava class exception rand 單元 當前 math pri 時有
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
public class SemaphoreTest {
public static void main(String[] args) {
ExecutorService service = Executors.newCachedThreadPool();
final Semaphore sp = new Semaphore(5);
for(int i=0;i<10;i++){
Runnable runnable = new Runnable(){
public void run(){
try {
sp.acquire();
} catch (InterruptedException e1) {
e1.printStackTrace();
}
System.out.println("線程" + Thread.currentThread().getName() +
"進入，當前已有" + (5-sp.availablePermits()) + "個並發");
try {
Thread.sleep((long)(Math.random()*10000));
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("線程" + Thread.currentThread().getName() +
"即將離開");
sp.release();
//下面代碼有時候執行不準確，因為其沒有和上面的代碼合成原子單元
System.out.println("線程" + Thread.currentThread().getName() +
"已離開，當前已有" + (3-sp.availablePermits()) + "個並發");
}
};
service.execute(runnable);
}
}
}
控制能同時有幾個線程並發Semaphore