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move prompts from margin to main column on small screens...
move prompts from margin to main column on small screens This is mainly for nbviewer, but the relevant CSS lives in IPython.

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restarter.py
114 lines | 3.9 KiB | text/x-python | PythonLexer
"""A basic kernel monitor with autorestarting.
This watches a kernel's state using KernelManager.is_alive and auto
restarts the kernel if it dies.
It is an incomplete base class, and must be subclassed.
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2013 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
from IPython.config.configurable import LoggingConfigurable
from IPython.utils.traitlets import (
Instance, Float, Dict, Bool, Integer,
)
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
class KernelRestarter(LoggingConfigurable):
"""Monitor and autorestart a kernel."""
kernel_manager = Instance('IPython.kernel.KernelManager')
time_to_dead = Float(3.0, config=True,
help="""Kernel heartbeat interval in seconds."""
)
restart_limit = Integer(5, config=True,
help="""The number of consecutive autorestarts before the kernel is presumed dead."""
)
_restarting = Bool(False)
_restart_count = Integer(0)
callbacks = Dict()
def _callbacks_default(self):
return dict(restart=[], dead=[])
def start(self):
"""Start the polling of the kernel."""
raise NotImplementedError("Must be implemented in a subclass")
def stop(self):
"""Stop the kernel polling."""
raise NotImplementedError("Must be implemented in a subclass")
def add_callback(self, f, event='restart'):
"""register a callback to fire on a particular event
Possible values for event:
'restart' (default): kernel has died, and will be restarted.
'dead': restart has failed, kernel will be left dead.
"""
self.callbacks[event].append(f)
def remove_callback(self, f, event='restart'):
"""unregister a callback to fire on a particular event
Possible values for event:
'restart' (default): kernel has died, and will be restarted.
'dead': restart has failed, kernel will be left dead.
"""
try:
self.callbacks[event].remove(f)
except ValueError:
pass
def _fire_callbacks(self, event):
"""fire our callbacks for a particular event"""
for callback in self.callbacks[event]:
try:
callback()
except Exception as e:
self.log.error("KernelRestarter: %s callback %r failed", event, callback, exc_info=True)
def poll(self):
self.log.debug('Polling kernel...')
if not self.kernel_manager.is_alive():
if self._restarting:
self._restart_count += 1
else:
self._restart_count = 1
if self._restart_count >= self.restart_limit:
self.log.warn("KernelRestarter: restart failed")
self._fire_callbacks('dead')
self._restarting = False
self._restart_count = 0
self.stop()
else:
self.log.info('KernelRestarter: restarting kernel (%i/%i)',
self._restart_count,
self.restart_limit
)
self._fire_callbacks('restart')
self.kernel_manager.restart_kernel(now=True)
self._restarting = True
else:
if self._restarting:
self.log.debug("KernelRestarter: restart apparently succeeded")
self._restarting = False