使用静态内部类单例模式创建线程池

使用静态内部类单例模式创建线程池

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import lombok.extern.slf4j.Slf4j;

import java.util.concurrent.*;

/**
 * @Author cjg
 * @description：单例定义线程池
 * @Date 2022/04/26 11:51
 **/
public class ThreadUtils {

    //多线程查询
    public ThreadUtils(){}

    /**
     * 定义cpu核数+3数量的线程池
     * 静态内部类方式使用时创建，线程安全
     */
    public static class SingletonHolder{
        // 获取cpu 的核数
        static int max = Runtime.getRuntime().availableProcessors();
        private static ExecutorService threadPool = new ThreadPoolExecutor(
                2,                          //核心线程池大小
                max,                                    //最大的线程池大小
                3,                         //超时了没有人调用就会释放
                TimeUnit.SECONDS,                       //超时单位
                new LinkedBlockingDeque<>(3),   //阻塞队列
                Executors.defaultThreadFactory(),       //线程工厂 创建线程的 一般不用动
                new ThreadPoolExecutor.AbortPolicy()    //拒绝策略
        );
    }

    public static ExecutorService newInstance() {
        return SingletonHolder.threadPool;
    }

}
@Slf4j
class Main{
    public static void main(String[] args) {
        System.out.println(Runtime.getRuntime().availableProcessors());
        ExecutorService service = ThreadUtils.newInstance();
        for (int i = 0; i < 8; i++) {
            int finalI = i;
            service.submit(() -> {
                log.info("使用线程池实例"+service.toString());
                try {
                    log.info("模拟解析文件开始，调用线程池的线程:"+Thread.currentThread().getName());
                    Thread.sleep(1000);
                    log.info("结束------"+ finalI);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });
        }

    }
}


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Exception in thread "main" java.util.concurrent.RejectedExecutionException: Task java.util.concurrent.FutureTask@7c0c77c7 rejected from java.util.concurrent.ThreadPoolExecutor@5cee5251[Running, pool size = 4, active threads = 4, queued tasks = 3, completed tasks = 0]
	at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
	at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
	at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
	at java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:112)
	at cn.gzsendi.modules.utils.Main.main(ThreadUtils.java:47)
2022-04-26 14:32:25,176  INFO [pool-1-thread-1] cn.gzsendi.modules.utils.Main.lambda$main$0:48 - 使用线程池实例java.util.concurrent.ThreadPoolExecutor@5cee5251[Running, pool size = 4, active threads = 4, queued tasks = 3, completed tasks = 0]
2022-04-26 14:32:25,183  INFO [pool-1-thread-1] cn.gzsendi.modules.utils.Main.lambda$main$0:50 - 模拟解析文件开始，调用线程池的线程:pool-1-thread-1
2022-04-26 14:32:25,176  INFO [pool-1-thread-4] cn.gzsendi.modules.utils.Main.lambda$main$0:48 - 使用线程池实例java.util.concurrent.ThreadPoolExecutor@5cee5251[Running, pool size = 4, active threads = 4, queued tasks = 3, completed tasks = 0]
2022-04-26 14:32:25,176  INFO [pool-1-thread-2] cn.gzsendi.modules.utils.Main.lambda$main$0:48 - 使用线程池实例java.util.concurrent.ThreadPoolExecutor@5cee5251[Running, pool size = 4, active threads = 4, queued tasks = 3, completed tasks = 0]
2022-04-26 14:32:25,184  INFO [pool-1-thread-4] cn.gzsendi.modules.utils.Main.lambda$main$0:50 - 模拟解析文件开始，调用线程池的线程:pool-1-thread-4
2022-04-26 14:32:25,184  INFO [pool-1-thread-2] cn.gzsendi.modules.utils.Main.lambda$main$0:50 - 模拟解析文件开始，调用线程池的线程:pool-1-thread-2
2022-04-26 14:32:25,176  INFO [pool-1-thread-3] cn.gzsendi.modules.utils.Main.lambda$main$0:48 - 使用线程池实例java.util.concurrent.ThreadPoolExecutor@5cee5251[Running, pool size = 4, active threads = 4, queued tasks = 3, completed tasks = 0]
2022-04-26 14:32:25,185  INFO [pool-1-thread-3] cn.gzsendi.modules.utils.Main.lambda$main$0:50 - 模拟解析文件开始，调用线程池的线程:pool-1-thread-3
2022-04-26 14:32:26,186  INFO [pool-1-thread-4] cn.gzsendi.modules.utils.Main.lambda$main$0:52 - 结束------6
2022-04-26 14:32:26,186  INFO [pool-1-thread-3] cn.gzsendi.modules.utils.Main.lambda$main$0:52 - 结束------5
2022-04-26 14:32:26,186  INFO [pool-1-thread-2] cn.gzsendi.modules.utils.Main.lambda$main$0:52 - 结束------1
2022-04-26 14:32:26,187  INFO [pool-1-thread-3] cn.gzsendi.modules.utils.Main.lambda$main$0:48 - 使用线程池实例java.util.concurrent.ThreadPoolExecutor@5cee5251[Running, pool size = 4, active threads = 4, queued tasks = 1, completed tasks = 2]
2022-04-26 14:32:26,187  INFO [pool-1-thread-3] cn.gzsendi.modules.utils.Main.lambda$main$0:50 - 模拟解析文件开始，调用线程池的线程:pool-1-thread-3
2022-04-26 14:32:26,187  INFO [pool-1-thread-2] cn.gzsendi.modules.utils.Main.lambda$main$0:48 - 使用线程池实例java.util.concurrent.ThreadPoolExecutor@5cee5251[Running, pool size = 4, active threads = 4, queued tasks = 1, completed tasks = 2]
2022-04-26 14:32:26,188  INFO [pool-1-thread-2] cn.gzsendi.modules.utils.Main.lambda$main$0:50 - 模拟解析文件开始，调用线程池的线程:pool-1-thread-2
2022-04-26 14:32:26,188  INFO [pool-1-thread-4] cn.gzsendi.modules.utils.Main.lambda$main$0:48 - 使用线程池实例java.util.concurrent.ThreadPoolExecutor@5cee5251[Running, pool size = 4, active threads = 4, queued tasks = 0, completed tasks = 3]
2022-04-26 14:32:26,189  INFO [pool-1-thread-4] cn.gzsendi.modules.utils.Main.lambda$main$0:50 - 模拟解析文件开始，调用线程池的线程:pool-1-thread-4
2022-04-26 14:32:26,186  INFO [pool-1-thread-1] cn.gzsendi.modules.utils.Main.lambda$main$0:52 - 结束------0
2022-04-26 14:32:27,201  INFO [pool-1-thread-4] cn.gzsendi.modules.utils.Main.lambda$main$0:52 - 结束------4
2022-04-26 14:32:27,201  INFO [pool-1-thread-2] cn.gzsendi.modules.utils.Main.lambda$main$0:52 - 结束------3
2022-04-26 14:32:27,201  INFO [pool-1-thread-3] cn.gzsendi.modules.utils.Main.lambda$main$0:52 - 结束------2

当线程数大于线程池执行拒绝策略