"""A basic in process kernel monitor with autorestarting.
This watches a kernel's state using KernelManager.is_alive and auto
restarts the kernel if it dies.
"""
# Copyright (c) Jupyter Development Team.
# Distributed under the terms of the Modified BSD License.
from __future__ import absolute_import
import warnings
from zmq.eventloop import ioloop
from jupyter_client.restarter import KernelRestarter
from traitlets import (
Instance,
)
class IOLoopKernelRestarter(KernelRestarter):
"""Monitor and autorestart a kernel."""
loop = Instance('tornado.ioloop.IOLoop')
def _loop_default(self):
warnings.warn("IOLoopKernelRestarter.loop is deprecated in jupyter-client 5.2",
DeprecationWarning, stacklevel=4,
)
return ioloop.IOLoop.current()
_pcallback = None
def start(self):
"""Start the polling of the kernel."""
if self._pcallback is None:
self._pcallback = ioloop.PeriodicCallback(
self.poll, 1000*self.time_to_dead,
)
self._pcallback.start()
def stop(self):
"""Stop the kernel polling."""
if self._pcallback is not None:
self._pcallback.stop()
self._pcallback = None