.recv()/.send()REQ/REPzmq.DONTWAIT.recv().send()

But the thing is, the flow needs to be lock step, so:

server.recv()client.send()client.recv()server.send()

And between 3 and 4 the weirdness starts, because they are async.

When the client has sent a message and the server has not received it yet but client tries to receive a response, the lock step is no lock step any more. 

zmq.DOBLOCKzmq.DONTWAIT

Or did I get something wrong here?

EDIT:

I am using this go binding in C for zeromq: https://godoc.org/github.com/pebbe/zmq4#Type

.recv()flag

This is the current code I got to make a workaround which feels somewhat ugly:

package connection

import (
  "zmq4"
  "fmt"
  "time"
)


const ERRTMPUNAV="resource temporarily unavailable"


func checkError(e error){
  if e != nil {
    panic(e)
  }
}


func CreateRepNode(address string,onMessage chan<- string,send <-chan string,closeConn <-chan bool){
  stop:=false
  socket,err:=zmq4.NewSocket(zmq4.REP)
  checkError(err)
  err=socket.Bind(address)
  checkError(err)
  go func(socket *zmq4.Socket){
    for {
      msg,err:=socket.Recv(zmq4.DONTWAIT)
      fmt.Println("server message"+msg)
      if stop==true {
        return
      }
      if err != nil {
        rateLimit := time.Tick(100 * time.Millisecond)
    <-rateLimit
    continue
      }
      checkError(err)
      onMessage<-msg
      rep:=<-send
      _,err=socket.Send(rep,zmq4.DONTWAIT)
    }
  }(socket)
  <-closeConn
  stop=true
}


func CreateReqNode(address string,onMessage chan<- string,send <-chan string,closeConn <-chan bool){
  stop:=false
  socket,err:=zmq4.NewSocket(zmq4.REQ)
  checkError(err)
  err=socket.Connect(address)
  checkError(err)
  go func(){
    for {
      msg:=<-send
      if stop==true {
        return
      }
      _,err:=socket.Send(msg,zmq4.DONTWAIT)
      for {
        msg,err=socket.Recv(zmq4.DONTWAIT)
        fmt.Println("client got message "+msg)
        if err!=nil {
          if err.Error()==ERRTMPUNAV {
            w:=time.Tick(100*time.Millisecond)
            <-w
            continue
          }
        }
        break
      }
      onMessage<-msg
    }
  }()

  <-closeConn
  stop=true
}