Starting an ipython kernel outside the main thread

ipkernelapp_outside_main_thread.py

import threading
import sys
import signal
# this is the heavy monkey-patching that actually works
# i.e. you can start the kernel fine and connect to it e.g. via
# ipython console --existing
# signal.signal = lambda *args, **kw: None
from IPython.zmq.ipkernel import IPKernelApp

app = IPKernelApp.instance()

def target(app):
    _stdout, _stderr = sys.stdout, sys.stderr
    try:
        # uncomment the next line and you can start the kernel fine
        # outside of the main thread although trying to connect to it,
        # e.g. via ipython console --existing get you 
        # ValueError: signal only works in main thread
        # app.init_signal = lambda *args, **kw: None
        app.initialize()
        app.start()
    except Exception as e:
        sys.stdout, sys.stderr = _stdout, _stderr
        import traceback
        traceback.print_exc()

t = threading.Thread(target=target, args=(app,))
t.start()