Start an IPython cluster with subprocess

ipcluster_launcher.py

"""
Creates a task interface.

Change to 

view = rc[:]

for a direct interface.
"""
from IPython.parallel import Client

def launch_cluster(n=4, *args):
    from subprocess import Popen, PIPE
    return Popen(['ipcluster', 'start', '-n', str(n)] + list(args), stdout=PIPE, stderr=PIPE)

try:
    rc = Client()
    view = rc.load_balanced_view()
except IOError:
    launch_cluster()
    import time
    time.sleep(5)
    rc = Client()
    view = rc.load_balanced_view()