runtime: sockets closed by remote peer may remain undetected by poller #6753
Description
I have observed a network TCP server blocked on a Write although the client (Go program located on a remote machine) has closed the connection. So far I have been unable to produce a minimal reproducer. My hypothesis is that the poller is not handling EPOLLRDHUP correctly. map epoll_ctl(2) says that it means: "Stream socket peer closed connection, or shut down writing half of connection." But when obtaining EPOLLRDHUP from the socket the poller wakes up WaitRead() but not WaitWrite(), so if the EPOLLRDHUP was generated by a remote close, waiting writers will never wake up (one would expect something like "connection reset by peer"). Using linux/amd64.