epoll_wait返回Bad文件描述符

Question

我正在用C ++编写一个多线程服务器。主事件循环如下所示：

for (;loop_enabled_;)
{
    int ret = epoll_wait(epollfd, events, epoll_event_buf_size(), -1);
    if (ret >= 0)
        handle_events(events, events + ret);
    else
    {
        std::error_code ec(errno, std::system_category());
        logger->critical("Error in epoll_wait: {}", ec.message());
        throw std::system_error(ec);
    }
}

但是，在极少数情况下epoll_wait可能会失败Bad file descriptor，即使它已成功完成多次迭代。

根据man epoll_wait：

  

错误

EBADF  epfd is not a valid file descriptor.

EFAULT The memory area pointed to by events is not accessible with write permissions.

EINTR  The call was interrupted by a signal handler before either (1) any of the requested events occurred or (2) the timeout expired; see signal(7).

EINVAL epfd is not an epoll file descriptor, or maxevents is less than or equal to zero.

EBADF建议epollfd在我的代码中无效，但由于它已完成多次迭代，invalid在这里意味着什么？在close之前epoll_ctl(EPOLL_CTL_DEL)会导致此吗？