Greenline Test

config.toml

[[rail]]
name     = "broadcast"
pattern  = "pub/sub"
ingress  = 5000
egress   = 6000

[[rail]]
name     = "conversation"
pattern  = "req/rep"
ingress  = 7000
egress   = 8000

publish.py

#!/usr/bin/env python3

from zmq              import Context, PUB
from zmq.log.handlers import PUBHandler

import time

# setup
ctx      = Context()
pub_sock = ctx.socket(PUB)

# publisg msg to channel
pub_sock.connect('tcp://localhost:5000')
pub_sock.send_multipart([b'', b'Hello'])
time.sleep(1)

subscribe.py

#!/usr/bin/env python3

from zmq import Context, SUB, SUBSCRIBE

ctx = Context()
s = ctx.socket(SUB)
s.connect('tcp://localhost:6000')
s.setsockopt(SUBSCRIBE, b'')

topic, msg = s.recv_multipart()
print("on topic: %s, %s" % (topic, msg))

The publisher's send does not appear in the greenline standard out log nor does the subscriber receive a message. However, if I am not running greenline and allow publish.py to bind then it works.

Blocking and non-blocking variants of subscriber:

#!/usr/bin/env python
import os
import zmq
from contextlib import suppress
ctxt = zmq.Context()

s = ctxt.socket(zmq.SUB)
s.connect('tcp://localhost:6000')
s.setsockopt(zmq.SUBSCRIBE, b'') 

print(os.getpid())

def blocking_recv():
    topic, msg = s.recv_multipart()
    return topic, msg

def nonblocking_recv():
    iters = 0
    while True:
        iters += 1 
        with suppress(zmq.error.Again):
            topic, msg = s.recv_multipart(zmq.NOBLOCK)
            break
    print('%d iterations before receipt' % (iters))
    return topic, msg

while True:
    print(nonblocking_recv())