Check if kernel is alive during cell execution

[davidbrochart]

Fixes #88

[davidbrochart]

I don't know about the failures, they are related to pyzmq and were already present in the last commit.

[davidbrochart]

The failing test is caused by the deprecation warning, I opened an issue in jupyter/jupyter_client#558.

[MSeal]

LGTM, I ran some papermill tests and calls and it seems solid. Thanks for tackling. Let's have the jupyter_client discussion on the issue you opened and make a decision about if we patch the test for now or get a change upstream made.

[davidbrochart]

Looks like we got bitten by jupyter/jupyter_client#487:

E         + Exception in thread Thread-3:
E         + Traceback (most recent call last):
E         +   File "/opt/hostedtoolcache/Python/3.8.3/x64/lib/python3.8/threading.py", line 932, in _bootstrap_inner
E         +     self.run()
E         +   File "/home/runner/work/nbclient/nbclient/.tox/py38/lib/python3.8/site-packages/ipykernel/heartbeat.py", line 93, in run
E         +     self._bind_socket()
E         +   File "/home/runner/work/nbclient/nbclient/.tox/py38/lib/python3.8/site-packages/ipykernel/heartbeat.py", line 74, in _bind_socket
E         +     self._try_bind_socket()
E         +   File "/home/runner/work/nbclient/nbclient/.tox/py38/lib/python3.8/site-packages/ipykernel/heartbeat.py", line 61, in _try_bind_socket
E         +     return self.socket.bind('%s://%s' % (self.transport, self.ip) + c + str(self.port))
E         +   File "zmq/backend/cython/socket.pyx", line 550, in zmq.backend.cython.socket.Socket.bind
E         +   File "zmq/backend/cython/checkrc.pxd", line 26, in zmq.backend.cython.checkrc._check_rc
E         + zmq.error.ZMQError: Address already in use

Relaunching tests.

[davidbrochart]

@MSeal I will be AFK for a few days, I let you squash and merge if you think this is fine.

[MSeal]

Thanks so much for getting this fixed. I'll kick off a patch release.

[choldgraf]

wahoo! 🥇