Synchronize reads and writes to TCP socket

Question

I'm trying to communicate with a TCP server which responds to messages:

package main

import (
    "net"
    "log"
)

func handleErr(err error) {
    if err != nil {
        log.Fatal(err)
    }
}

func main() {

    // connect
    host := "1.2.3.4:5678"
    conn, err := net.Dial("tcp", host)
    handleErr(err)
    defer conn.Close()

    // write to socket
    message := "Test\n"
    conn.Write([]byte(message))

    // read from socket
    // (assume response is 'Test\n')
    reply := make([]byte, 1024)
    conn.Read(reply)
    log.Println(string(reply))

}

What I'm trying to accomplish is to send a message to the socket-server on the other end, wait for a response and then process it. I seem to be having trouble with properly syncing these write/read operation to be timed correctly - right now the read action seems to block the write; I'm assuming this happens due to the async nature of Go. What's an idiomatic way to do this? Is it goroutines? A continuous for { .. } loop for the reader? A sync.Wait mechanism? Help is appreciated. thanks.

Answer 1

Your code should work should work just fine. Golang is dead simple, there is no need for thinking about synchronizing read/write calls.

[EDIT] To be clear: Go's networking model is synchronous, just like any old style socket program. Go uses internally efficient tricks to deal with it but as a programmer you have the comfort to program sequential code, which is the whole point about goroutines. Goroutines can be like threads but they are so cheap that you can create a LOT of them (a.k.a. fibers).

Keep in mind that TCP might not send every piece in one shot. You should always check the return values to be sure that everything has been sent. Maybe the server just receives a part of the message and waits for more, but your client is already waiting for an answer? Just a guess.