示例模拟10000次请求,每次并发数为100,每次请求,计数器加1,最后输出计数器值。 上代码:
package concurrent;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
/**
* @Auther:zhl
* @Date:2019/7/13
* @Description: 并发测试
*/
public class ConcurrentSample {
//并发线程数量
private static int users = 100;
//访问次数
private static int count = 10000;
//访问总量
private static int number = 0;
public static void main(String[] args) {
//定义线程池
ExecutorService executorService = Executors.newCachedThreadPool();
//并发量
Semaphore semaphore = new Semaphore(users);
for (int i = 0; i < count; i++) {
executorService.execute(() -> {
try {
semaphore.acquire();
add();
semaphore.release();
} catch (Exception e) {
e.printStackTrace();
}
});
}
try {
Thread.sleep(3000);
} catch (Exception e) {
e.printStackTrace();
}
executorService.shutdown();
System.out.println(number);
}
public static void add() {
number++;
}
}
计数器:9997 计数器:10000 计数器:9997 每次输出结果不一致,这都是并发导致的