It's possible that something is wrong with `sync` and TCP ports --- although the test suite at least includes that combination --- but can you provide a complete program?
For example, I'm interested in what `handle-rdy-to-send` does. In the part that you show, the function will be triggered when one byte is available on stdin. If `handle-rdy-to-send` tries to read more bytes than are immediately available, then it can block; i.e., the blocking part could be in `handle-rdy-to-send`, not in `sync`. That would also explain why using `sync/timeout` doesn't change anything. Again, that's just an example of what might be wrong other than `sync`. A complete program would let us sort out the possibilities. At Sun, 14 Sep 2014 06:57:34 -0500, Brett Stahlman wrote: > Hello, > > I have the following loop in a tcp client program that sends forms typed by > user at the terminal to a listening server, and receives such forms typed by > other clients (broadcast to all clients by the server). > > (define server-msg-evt (wrap-evt in handle-server-msg)) > (define rdy-to-send-evt (wrap-evt (standard-input-port) handle-rdy-to-send)) > > (let loop () > (sync rdy-to-send-evt server-msg-evt) > (loop)) > > The problem is that the server-msg-evt isn't reliably ready when the server > flushes a message. I know the messages are being sent and flushed properly > by > the server because if I type a new form on stdin and hit enter, I see the > following sequence: > > 1. Client processes new stdin form in handle-rdy-to-send > 2. Client loops and calls sync > 3. The server-msg-evt is *immediately* ready, and client handles the > message in handle-server-msg. > Note: The message handled in step 3 may have been sent long before, but > the client remained blocked in sync until the (unrelated) stdin event > unblocked it. > > The really weird part is that the client blocks in this manner even if I > change the sync to a sync/timeout! > > Any clue as to what could be going on here? I'm running both client and > server > in a DOS box on a Windows 7 machine. > > Thanks, > Brett Stahlman > ____________________ > Racket Users list: > http://lists.racket-lang.org/users ____________________ Racket Users list: http://lists.racket-lang.org/users
