test.py

gistfile1.py

import sys
import zmq
import time
import subprocess
import atexit

ctx = zmq.Context(1)
sock = ctx.socket(zmq.XREQ)
sock.bind('tcp://127.0.0.1:12345')

proc = subprocess.Popen([sys.executable, 'test2.py'])
time.sleep(0.1)
proc1 = subprocess.Popen([sys.executable, 'test2.py'])
atexit.register(proc1.terminate)

time.sleep(0.1)
sock.send(b"a1", zmq.SNDMORE)
time.sleep(0.1)

proc.terminate()
proc.wait()

time.sleep(0.1)
sock.send(b"b1", zmq.SNDMORE|zmq.NOBLOCK)
time.sleep(0.1)
proc = subprocess.Popen([sys.executable, 'test2.py'])
time.sleep(0.1)

sock.send(b"c1", zmq.NOBLOCK)
sock.send(b"a2", zmq.SNDMORE|zmq.NOBLOCK)
sock.send(b"b2", zmq.SNDMORE|zmq.NOBLOCK)
sock.send(b"c2", zmq.NOBLOCK)
sock.send(b"a3", zmq.SNDMORE|zmq.NOBLOCK)
sock.send(b"b3", zmq.SNDMORE|zmq.NOBLOCK)
sock.send(b"c3", zmq.NOBLOCK)
try:
    proc.wait()
except:
    proc.terminate()
finally:
    proc1.terminate()
ctx = zmq.Context(1)

test2.py

import zmq
import time

ctx = zmq.Context(1)
sock = ctx.socket(zmq.XREP)
sock.connect('tcp://127.0.0.1:12345')
while True:
    print("MSG", sock.recv_multipart())