接下来的几篇分析当中都会以这段问题代码为基础进行讲解……(对于数量 +1 业务:5000个请求,200个并发)
包括接下来有四个注解(标记而已)代表不同含义:
- @NotRecommend:课程里用来标记【不推荐】的类或者写法
- @NotThreadSafe:课程里用来标记【线程不安全】的类或者写法
- @Recommend:课程里用来标记【推荐】的类或者写法
- @ThreadSafe:课程里用来标记【线程安全】的类或者写法
package com.mmall.concurrency;
import com.mmall.concurrency.annoations.NotThreadSafe;
import lombok.extern.slf4j.Slf4j;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
@Slf4j
@NotThreadSafe
public class ConcurrencyTest {
// 请求总数
public static int clientTotal = 5000;
// 同时并发执行的线程数
public static int threadTotal = 200;
public static int count = 0;
public static void main(String[] args) throws Exception {
ExecutorService executorService = Executors.newCachedThreadPool();
final Semaphore semaphore = new Semaphore(threadTotal);
final CountDownLatch countDownLatch = new CountDownLatch(clientTotal);
for (int i = 0; i < clientTotal; i++) {
executorService.execute(() -> {
try {
semaphore.acquire();
add();
semaphore.release();
} catch (Exception e) {
log.error("exception", e);
}
countDownLatch.countDown();
});
}
countDownLatch.await();
executorService.shutdown();
log.info("count:{}", count);
}
private static void add() {
count++;
}
}