ACE_Dev_Poll_Reactor出现了死锁？

Question

在ACE_Dev_Poll_Reactor::dispatch_io_event中找到了这段：

const __uint32_t err_event = EPOLLHUP | EPOLLERR;

const ACE_HANDLE handle = this->event_.data.fd;
__uint32_t revents = this->event_.events;

  // Figure out what to do first in order to make it easier to manage
        // the bit twiddling and possible pfds increment before releasing
        // the token for dispatch.
        // Note that if there's an error (such as the handle was closed
        // without being removed from the event set) the EPOLLHUP and/or
        // EPOLLERR bits will be set in revents.
eh = info->event_handler;
        if (ACE_BIT_ENABLED (revents, out_event))
        {
            disp_mask = ACE_Event_Handler::WRITE_MASK;
            callback = &ACE_Event_Handler::handle_output;
            ACE_CLR_BITS (revents, out_event);
        }
        else if (ACE_BIT_ENABLED (revents, exc_event))
        {
            disp_mask = ACE_Event_Handler::EXCEPT_MASK;
            callback = &ACE_Event_Handler::handle_exception;
            ACE_CLR_BITS (revents, exc_event);
        }
        else if (ACE_BIT_ENABLED (revents, in_event))
        {
            disp_mask = ACE_Event_Handler::READ_MASK;
            callback = &ACE_Event_Handler::handle_input;
            ACE_CLR_BITS (revents, in_event);
        }
        else if (ACE_BIT_ENABLED (revents, err_event))
        {
            this->remove_handler_i (handle,
                ACE_Event_Handler::ALL_EVENTS_MASK,
                grd,
                info->event_handler);

        出现 ACE_BIT_ENABLED (revents, err_event)条件为真，说明文件描述符发生错误或被挂断，但小弟不明白ACE_Dev_Poll_Reactor在什么情况下出现文件描述符发生错误，请各位高手帮忙看看，谢谢了！

Answer 1

自顶一下，期待高手帮忙，谢谢！