[zeromq-dev] hitting file descriptor using gevent

[Chuck Remes]

On Jul 10, 2011, at 8:59 AM, Tim Cooijmans wrote:

> I boiled it down to this simulation:
> Front-end-server:
> def sendmessage(i):
>    # Get context
>    context = zmq.Context()
>    socket = context.socket(zmq.REQ)
>    socket.connect("tcp://127.0.0.1:5000")
> 
>    # Send message
>    socket.send(str(i))
>    print("Send: " + str(i))
> 
>    # Wait for confirmation
>    socket.recv()
>    print("OK: " + str(i))
> 
> all = []
> for i in range(10):
>    thread = gevent.spawn(sendmessage, i)
>    all.append(thread) 
> gevent.joinall(all)

Are you creating a new context and socket every time you send a message? If so, that's a major flaw.

My suggestion is to create only a single context (it's *extremely* rare that you need more than one) and use it to pre-allocate each socket as you spawn each thread. 

e.g.

def sendmessage(socket, i):
  # blah

context = zmq.Context()
for i in range(1):
    socket = context.socket(zmq.REQ)
    socket.connect("tcp://127.0.0.1:5000")
    thread = gevent.spawn(sendmessage, socket, i)
    all.append(thread)


> Which works fine as long as there are less like 70 clients. Above this the
> "frontend-server" is hitting the file descriptor limit. A possible solution
> is to push the file descriptor limit up but this doesn't seem like the right
> thing to do to me. 
> What is the best way to achieve my goals? Should I abandon the REQ-XREP
> architecture?

Hitting the limit after 70 clients seems rather early. You probably need to provide a gist of *all* of the code because there might be something else going on here. Your snippet is too short to figure out the issue.

cr