线程池不允许使用Executors去创建，而是通过ThreadPoolExecutor的方式

public Executor taskScheduler(){
    /// return Executors.newScheduledThreadPool(100);
}

线程池不允许使用Executors去创建，而是通过ThreadPoolExecutor的方式，这样的处理方式让写的同学更加明确线程池的运行规则，规避资源耗尽的风险。 说明：Executors各个方法的弊端：
1）newFixedThreadPool和newSingleThreadExecutor:
  主要问题是堆积的请求处理队列可能会耗费非常大的内存，甚至OOM。
2）newCachedThreadPool和newScheduledThreadPool:
  主要问题是线程数最大数是Integer.MAX_VALUE，可能会创建数量非常多的线程，甚至OOM。

Positive example 1：

//org.apache.commons.lang3.concurrent.BasicThreadFactory
ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(1,
    new BasicThreadFactory.Builder().namingPattern("example-schedule-pool-%d").daemon(true).build());

Positive example 2：

ThreadFactory namedThreadFactory = new ThreadFactoryBuilder()
    .setNameFormat("demo-pool-%d").build();

//Common Thread Pool
ExecutorService pool = new ThreadPoolExecutor(5, 200,
    0L, TimeUnit.MILLISECONDS,
    new LinkedBlockingQueue(1024), namedThreadFactory, new ThreadPoolExecutor.AbortPolicy());

pool.execute(()-> System.out.println(Thread.currentThread().getName()));
pool.shutdown();//gracefully shutdown

Positive example 3：

    
    
    


    
        
    

//in code
userThreadPool.execute(thread);