Java中在子线程中获取固定大小的连接池出现错误，如果解释？

Question

问题1. 不太好描述，直接看代码吧

public class QueueConsumer extends EndPoint implements Runnable {

    // 线程池

    private ExecutorService executor = null;

    public QueueConsumer(String endPointName, String hosts, String ports,

            String username, String password) throws Exception {

        super(endPointName, hosts, ports, username, password);

        // 初始化线程池

        executor = Executors.newCachedThreadPool();

    }

    @Override

    public void run() {

        try {

            QueueingConsumer consumer = new QueueingConsumer(channel);

            channel.basicConsume(endPointName, false, consumer);

            while (true) {

                // 信息到达时

                Delivery delivery = consumer.nextDelivery();

                

                // 初始化业务线程对象

                BusinessClient businessClient = new BusinessClient(channel, delivery);

                // 执行任务

                executor.execute(businessClient);

            }

        } catch (Exception e) {

            LogUtil.printException("消息队列异常", e, LogUtil.LOG_LEVEL_ERROR);

        } finally {

            try {

                close();

            } catch (Exception e) {

                LogUtil.printException("关闭消息队列异常", e, LogUtil.LOG_LEVEL_ERROR);

public class BusinessClient implements Runnable {

    ... 省略

    

    // 主要代码

    List<Callable<Object>> taskList = new ArrayList<Callable<Object>>();

    for (BaseRequestData<BaseResponseData> queryData : queryDataLst) {

        QueryThread queryThread = new QueryThread(queryData);

        taskList.add(queryThread);

    }

    // 问题点：此处使用Executors.newFixedThreadPool(i)会抛出IllegalArgumentException

              但是使用Executors.newCachedThreadPool()则不会有问题.不是很理解，为什么此处不可以用newFixedThreadPool(i)?

              

    ExecutorService executor = Executors.newCachedThreadPool();

    List<Future<Object>> results = executor.invokeAll(taskList);

    executor.shutdown();

    

    ... 省略

}

问题2. 我如果定义一个线程池工厂，将线程池定义为static final，每个需要并发的地方都使用工厂来获得线程池，

   那么问题来了，我这个线程池会自动扩展或者释放线程吗？

   

   

纯粹自学的Java, 对于一些基础知识不是很理解，望不吝赐教！谢谢

Answer 1

Executors.newFixedThreadPool(i) 此处的i取值范围不对吧，如果你出现IllegalArgumentException，说明这个值是小于0的，这是不允许的。Executors.newFixedThreadPool(i) 最终会走下如下逻辑。public ThreadPoolExecutor(int corePoolSize,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int maximumPoolSize,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; long keepAliveTime,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; TimeUnit unit,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; BlockingQueue<Runnable> workQueue,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ThreadFactory threadFactory,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; RejectedExecutionHandler handler) {&nbsp; &nbsp; if (corePoolSize < 0 ||&nbsp; &nbsp; &nbsp; &nbsp; maximumPoolSize <= 0 ||&nbsp; &nbsp; &nbsp; &nbsp; maximumPoolSize < corePoolSize ||&nbsp; &nbsp; &nbsp; &nbsp; keepAliveTime < 0)&nbsp; &nbsp; &nbsp; &nbsp; throw new IllegalArgumentException();&nbsp; &nbsp; if (workQueue == null || threadFactory == null || handler == null)&nbsp; &nbsp; &nbsp; &nbsp; throw new NullPointerException();&nbsp; &nbsp; this.corePoolSize = corePoolSize;&nbsp; &nbsp; this.maximumPoolSize = maximumPoolSize;&nbsp; &nbsp; this.workQueue = workQueue;&nbsp; &nbsp; this.keepAliveTime = unit.toNanos(keepAliveTime);&nbsp; &nbsp; this.threadFactory = threadFactory;&nbsp; &nbsp; this.handler = handler;}