Can a socket be closed from another thread when a send / recv on the same socket is going on?

Question

Can a socket be closed from another thread when a send / recv on the same socket is going on?

Suppose one thread is in blocking recv call and another thread closes the s

Answer 1

If a thread is blocked on recv() or send() when the socket is closed by a different thread, the blocked thread will receive an error. However, it is difficult to detect the correct remedial action after receiving the error. This is because the file descriptor number associated with the socket may have been picked up by yet a different thread, and the blocked thread has now been woken up on an error for a "valid" socket. In such a case, the woken up thread should not call close() itself.

The woken up thread will need some way to differentiate whether the error was generated by the connection (e.g. a network error) that requires it to call close(), or if the error was generated by a different thread having called close() on it, in which case it should just error out without doing anything further to the socket.