Python Multiprocessing to publish to multiple topics

edit

I currently have a setup where I have about 10 shell scripts that listen to 10 different KNX addresses (using the shell command grouplisten) and publish their state to a ROS topic. These scripts can run in the background, so it's quite convenient to 'listen' to the state of these devices.

I tried to replace these 10 scripts with a single python program that basically does this:

1. Declare a subprocess.Popen for each device, to listen to its knx device.

   self.listen_stat = subprocess.Popen(self.cmds,stdout=subprocess.PIPE,preexec_fn=os.setsid)
   

2. Declare the node (in __main__) , and topic for each device ( in device.__init__()).

   class DeviceProp:
   def __init__(self):
     ...
     self.pub = rospy.Publisher(self.name,Int32,latch=True)
   

3. Call a talker function like so:

try:
  for device in device_props:
       p = multiprocessing.Process(target=device.device_talker)
       procs.append(p)
       p.start()
except (KeyboardInterrupt,rospy.ROSInterruptException,IOError) as e:
    for p in procs:
       p.join()

(The device_talker basically just publishes new data to device.pub)

What happens is that the logs suggest data is being published, but I don't see anything on when I subscribe to those topics or if I do rostopic echo. If I run rostopic pub from a new shell, I get the data on the topic as expected. I've also added a rospy.sleep(1) at multiple places (in loops too) so that even if I lose the first few messages, I _should_ get the later ones. But I don't.

Any suggestions on what I should do? (In case you are wondering why - I want to replace 10 scripts with 1 for easier code management. Also, Since I can store all address and device props in a yaml file, it will be trivial to add, or edit the configuration file).