使用CreateIoCompletionPort创建完成端口对象。

2.创建工作线程，在完成端口上执行并处理投递到完成端口上I/O请求。

3.向完成端口对象关联套接字句柄。

4.投递重叠发送和接受请求处理I/O。

-Completion port object CreateIoCompletionPort create. Create worker threads running on the completion port and handle delivery to the completion port on the I/O request. 3 socket handle objects related to the completion of the port. 4 delivery overlapping send and receive the request processing I/O.