Programming

We're doing that without any problem. We have one thread that blocks on the socket waiting for the server to send data; while another thread might independently send some data to the server. Works like a charm.

As mentioned By Coronna688, the best way for you to identify the problem (and for us to help you) is to write a minimalistic example - that compiles and show what your problem is.

Good Luck,
Loïc

I have a feeling that you have no idea what you are talking about. The SOCK_STREAM socket that you listen on is handling session queue. When you call accept() you end up with completely different socket to handle actual I/O for the TCP session.

This is supposed to be your reply to my answer, I guess?

If you read my answer carefully, you'll see that I just told the OP that it is not a problem to write/select at the same time on the established connection (the socket you obtained as result of accept).

writing on the listening socket doesn't make any sense, so I discarded this possibility. Though I couldn't absolutely sure from OP answer that s(he) not trying to do that.

Cheers, Loïc.

Why would you use select() on established connection when recv() is already blocking?

When for instance blocking forever is not acceptable, and a timeout is needed... This is a classical requirement for real-world systems, and select() is one of the many possible ways to fulfill it.

Cheers, Loïc

recv() is capable to timeout as it uses select syscall internally and timeout is configured with setsockopt(), putting one more select call in front just adds overhead.

Quoting yourself: I have a feeling that you have no idea what you are talking about Not all systems support SO_RCVTIMEO, so this last statement obviously doesn't make sense...

Your reasoning is excellent, but your basic assumptions are off. If you read carefully my posts, I just mentioned that it is possible to block on a socket, while sending data, since TCP is full-duplex. Nothing more, nothing less.

And even if people err (I personally do), I don't feel the need to treat them "maroons that have no idea about what they're talking about". We're all here to learn, and this can be achieved in a respectful way.

Just my 2c,
Loïc