线程池7个参数

ThreadPoolExecutor的重要参数：

corePoolSize:核心线程数

maximumpoolsize：最大线程数

keepAliveTime：多余的空闲线程的存活时间

unit：时间单位

workqueue：任务队列，被提交但尚未被执行的任务

threadFactory：生成线程池中工作线程的线程工厂，用于创建线程，一般默认的即可。

handler：拒绝策略

// cpu密集型，cpu数+1，选用最大线程数时参考
        System.out.println(Runtime.getRuntime().availableProcessors());
        ExecutorService executorService = new ThreadPoolExecutor(
                2,//核心线程数
                5,//最大线程数
                60,//缩容到核心线程数的等待时间
                TimeUnit.SECONDS,//缩容的时间单位
                new LinkedBlockingDeque<>(5),//等待队列
                Executors.defaultThreadFactory(),//线程工厂
                new ThreadPoolExecutor.AbortPolicy()//默认策略，直接抛出RejectExecutionException异常
        );
        /*
        * 拒接策略：
        * new ThreadPoolExecutor.AbortPolicy()//默认策略，直接抛出RejectExecutionException异常
          new ThreadPoolExecutor.CallerRunsPolicy()//不抛出异常，将任务回退给调用者
          new ThreadPoolExecutor.DiscardPolicy()//不抛出异常，抛弃无法执行的任务
          new ThreadPoolExecutor.DiscardOldestPolicy()//不抛出异常，抛弃队列中等待最久的，接受新任务
        * */
        try {
            for (int i = 0; i < 11; i++) {
                executorService.execute(() -> {
                    System.out.println(Thread.currentThread().getName());
                });
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            executorService.shutdown();
        }
//所报异常
java.util.concurrent.RejectedExecutionException: Task data.juc.TestThreadPool$$Lambda$1/1078694789@3b9a45b3 rejected from java.util.concurrent.ThreadPoolExecutor@7699a589[Running, pool size = 5, active threads = 0, queued tasks = 0, completed tasks = 10]
pool-1-thread-3
	at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2063)
pool-1-thread-4
	at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:830)
pool-1-thread-5
	at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1379)
pool-1-thread-3
	at data.juc.TestThreadPool.main(TestThreadPool.java:22)
pool-1-thread-2
pool-1-thread-3
pool-1-thread-5
pool-1-thread-4
pool-1-thread-1