Handling REQ/REP syncronization in eventlet

req_req.py

from eventlet.pools import Pool
from eventlet.timeout import Timeout

class SocketPool(Pool):
    """A pool of sockets connected to a component

    If a socket times out in use, simply close if before handing it back to the
    pool and it will be discarded and a replacement inserted into the pool."""

    def __init__(self, address, **kwargs):
        self.address = address
        super(SocketPool, self).__init__(**kwargs)

    def __str__(self):
        return self.address

    def __repr__(self):
        return "<SocketPool: %s>" % self

    def create(self):
        socket = zmq.Context().socket(zmq.REQ)
        socket.connect(self.address)
        socket.setsockopt(zmq.LINGER, 0)
        return socket

    def put(self, socket):
        """Wrapper around superclass put, replacing socket if closed"""
        if socket.closed:
            socket = self.create()
        super(SocketPool, self).put(socket)


def do_req_rep(destination_pool, message):
    with destination_pool.item() as socket:
        try:
            with Timeout():
                socket.send(message)
                return socket.recv()
        except TimeoutException:
            socket.close()
    

I should also have imported the greened version of zmq for this to work (from eventlet.green import zmq)

As mentioned in the article, timeouts work. The problem is that they are timeouts. For many cases the signalling from TCP would yield results much earlier.