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"""Base class to manage a running kernel"""
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# Copyright (c) IPython Development Team.
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# Distributed under the terms of the Modified BSD License.
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from __future__ import absolute_import
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from contextlib import contextmanager
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import os
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import re
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import signal
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import sys
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import time
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import warnings
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try:
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from queue import Empty # Py 3
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except ImportError:
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from Queue import Empty # Py 2
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import zmq
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from IPython.utils.importstring import import_item
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from IPython.utils.localinterfaces import is_local_ip, local_ips
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from IPython.utils.path import get_ipython_dir
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from IPython.utils.traitlets import (
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Any, Instance, Unicode, List, Bool, Type, DottedObjectName
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)
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from IPython.kernel import (
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launch_kernel,
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kernelspec,
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)
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from .connect import ConnectionFileMixin
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from .zmq.session import Session
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from .managerabc import (
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KernelManagerABC
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)
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class KernelManager(ConnectionFileMixin):
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"""Manages a single kernel in a subprocess on this host.
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This version starts kernels with Popen.
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"""
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# The PyZMQ Context to use for communication with the kernel.
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context = Instance(zmq.Context)
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def _context_default(self):
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return zmq.Context.instance()
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# the class to create with our `client` method
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client_class = DottedObjectName('IPython.kernel.blocking.BlockingKernelClient')
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client_factory = Type()
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def _client_class_changed(self, name, old, new):
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self.client_factory = import_item(str(new))
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# The kernel process with which the KernelManager is communicating.
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# generally a Popen instance
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kernel = Any()
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kernel_spec_manager = Instance(kernelspec.KernelSpecManager)
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def _kernel_spec_manager_default(self):
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return kernelspec.KernelSpecManager(ipython_dir=self.ipython_dir)
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kernel_name = Unicode(kernelspec.NATIVE_KERNEL_NAME)
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kernel_spec = Instance(kernelspec.KernelSpec)
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def _kernel_spec_default(self):
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return self.kernel_spec_manager.get_kernel_spec(self.kernel_name)
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def _kernel_name_changed(self, name, old, new):
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if new == 'python':
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self.kernel_name = kernelspec.NATIVE_KERNEL_NAME
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# This triggered another run of this function, so we can exit now
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return
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self.kernel_spec = self.kernel_spec_manager.get_kernel_spec(new)
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self.ipython_kernel = new in {'python', 'python2', 'python3'}
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kernel_cmd = List(Unicode, config=True,
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help="""DEPRECATED: Use kernel_name instead.
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The Popen Command to launch the kernel.
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Override this if you have a custom kernel.
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If kernel_cmd is specified in a configuration file,
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IPython does not pass any arguments to the kernel,
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because it cannot make any assumptions about the
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arguments that the kernel understands. In particular,
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this means that the kernel does not receive the
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option --debug if it given on the IPython command line.
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"""
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)
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def _kernel_cmd_changed(self, name, old, new):
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warnings.warn("Setting kernel_cmd is deprecated, use kernel_spec to "
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"start different kernels.")
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self.ipython_kernel = False
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ipython_kernel = Bool(True)
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ipython_dir = Unicode()
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def _ipython_dir_default(self):
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return get_ipython_dir()
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# Protected traits
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_launch_args = Any()
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_control_socket = Any()
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_restarter = Any()
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autorestart = Bool(False, config=True,
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help="""Should we autorestart the kernel if it dies."""
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)
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def __del__(self):
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self._close_control_socket()
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self.cleanup_connection_file()
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#--------------------------------------------------------------------------
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# Kernel restarter
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#--------------------------------------------------------------------------
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def start_restarter(self):
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pass
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def stop_restarter(self):
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pass
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def add_restart_callback(self, callback, event='restart'):
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"""register a callback to be called when a kernel is restarted"""
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if self._restarter is None:
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return
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self._restarter.add_callback(callback, event)
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def remove_restart_callback(self, callback, event='restart'):
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"""unregister a callback to be called when a kernel is restarted"""
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if self._restarter is None:
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return
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self._restarter.remove_callback(callback, event)
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#--------------------------------------------------------------------------
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# create a Client connected to our Kernel
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#--------------------------------------------------------------------------
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def client(self, **kwargs):
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"""Create a client configured to connect to our kernel"""
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if self.client_factory is None:
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self.client_factory = import_item(self.client_class)
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kw = {}
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kw.update(self.get_connection_info())
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kw.update(dict(
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connection_file=self.connection_file,
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session=self.session,
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parent=self,
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))
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# add kwargs last, for manual overrides
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kw.update(kwargs)
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return self.client_factory(**kw)
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#--------------------------------------------------------------------------
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# Kernel management
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#--------------------------------------------------------------------------
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def format_kernel_cmd(self, extra_arguments=None):
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"""replace templated args (e.g. {connection_file})"""
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extra_arguments = extra_arguments or []
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if self.kernel_cmd:
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cmd = self.kernel_cmd + extra_arguments
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else:
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cmd = self.kernel_spec.argv + extra_arguments
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ns = dict(connection_file=self.connection_file)
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ns.update(self._launch_args)
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pat = re.compile(r'\{([A-Za-z0-9_]+)\}')
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def from_ns(match):
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"""Get the key out of ns if it's there, otherwise no change."""
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return ns.get(match.group(1), match.group())
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return [ pat.sub(from_ns, arg) for arg in cmd ]
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def _launch_kernel(self, kernel_cmd, **kw):
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"""actually launch the kernel
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override in a subclass to launch kernel subprocesses differently
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"""
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return launch_kernel(kernel_cmd, **kw)
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# Control socket used for polite kernel shutdown
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def _connect_control_socket(self):
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if self._control_socket is None:
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self._control_socket = self.connect_control()
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self._control_socket.linger = 100
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def _close_control_socket(self):
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if self._control_socket is None:
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return
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self._control_socket.close()
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self._control_socket = None
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def start_kernel(self, **kw):
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"""Starts a kernel on this host in a separate process.
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If random ports (port=0) are being used, this method must be called
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before the channels are created.
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Parameters
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----------
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**kw : optional
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keyword arguments that are passed down to build the kernel_cmd
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and launching the kernel (e.g. Popen kwargs).
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"""
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if self.transport == 'tcp' and not is_local_ip(self.ip):
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raise RuntimeError("Can only launch a kernel on a local interface. "
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"Make sure that the '*_address' attributes are "
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"configured properly. "
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"Currently valid addresses are: %s" % local_ips()
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)
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# write connection file / get default ports
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self.write_connection_file()
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# save kwargs for use in restart
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self._launch_args = kw.copy()
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# build the Popen cmd
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extra_arguments = kw.pop('extra_arguments', [])
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kernel_cmd = self.format_kernel_cmd(extra_arguments=extra_arguments)
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if self.kernel_cmd:
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# If kernel_cmd has been set manually, don't refer to a kernel spec
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env = os.environ
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else:
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# Environment variables from kernel spec are added to os.environ
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env = os.environ.copy()
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env.update(self.kernel_spec.env or {})
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# launch the kernel subprocess
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self.kernel = self._launch_kernel(kernel_cmd, env=env,
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ipython_kernel=self.ipython_kernel,
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**kw)
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self.start_restarter()
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self._connect_control_socket()
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def request_shutdown(self, restart=False):
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"""Send a shutdown request via control channel
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On Windows, this just kills kernels instead, because the shutdown
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messages don't work.
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"""
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content = dict(restart=restart)
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msg = self.session.msg("shutdown_request", content=content)
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self.session.send(self._control_socket, msg)
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def finish_shutdown(self, waittime=1, pollinterval=0.1):
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"""Wait for kernel shutdown, then kill process if it doesn't shutdown.
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This does not send shutdown requests - use :meth:`request_shutdown`
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first.
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"""
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for i in range(int(waittime/pollinterval)):
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if self.is_alive():
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time.sleep(pollinterval)
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else:
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break
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else:
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# OK, we've waited long enough.
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if self.has_kernel:
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self._kill_kernel()
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def cleanup(self, connection_file=True):
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"""Clean up resources when the kernel is shut down"""
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if connection_file:
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self.cleanup_connection_file()
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self.cleanup_ipc_files()
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self._close_control_socket()
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def shutdown_kernel(self, now=False, restart=False):
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"""Attempts to the stop the kernel process cleanly.
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This attempts to shutdown the kernels cleanly by:
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1. Sending it a shutdown message over the shell channel.
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2. If that fails, the kernel is shutdown forcibly by sending it
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a signal.
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Parameters
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----------
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now : bool
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Should the kernel be forcible killed *now*. This skips the
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first, nice shutdown attempt.
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restart: bool
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Will this kernel be restarted after it is shutdown. When this
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is True, connection files will not be cleaned up.
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"""
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# Stop monitoring for restarting while we shutdown.
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self.stop_restarter()
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if now:
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self._kill_kernel()
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else:
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self.request_shutdown(restart=restart)
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# Don't send any additional kernel kill messages immediately, to give
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# the kernel a chance to properly execute shutdown actions. Wait for at
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# most 1s, checking every 0.1s.
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self.finish_shutdown()
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self.cleanup(connection_file=not restart)
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def restart_kernel(self, now=False, **kw):
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"""Restarts a kernel with the arguments that were used to launch it.
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If the old kernel was launched with random ports, the same ports will be
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used for the new kernel. The same connection file is used again.
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Parameters
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----------
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now : bool, optional
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If True, the kernel is forcefully restarted *immediately*, without
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having a chance to do any cleanup action. Otherwise the kernel is
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given 1s to clean up before a forceful restart is issued.
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In all cases the kernel is restarted, the only difference is whether
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it is given a chance to perform a clean shutdown or not.
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**kw : optional
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Any options specified here will overwrite those used to launch the
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kernel.
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"""
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if self._launch_args is None:
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raise RuntimeError("Cannot restart the kernel. "
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"No previous call to 'start_kernel'.")
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else:
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# Stop currently running kernel.
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self.shutdown_kernel(now=now, restart=True)
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# Start new kernel.
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self._launch_args.update(kw)
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self.start_kernel(**self._launch_args)
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@property
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def has_kernel(self):
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"""Has a kernel been started that we are managing."""
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return self.kernel is not None
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def _kill_kernel(self):
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"""Kill the running kernel.
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This is a private method, callers should use shutdown_kernel(now=True).
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"""
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if self.has_kernel:
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# Signal the kernel to terminate (sends SIGKILL on Unix and calls
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# TerminateProcess() on Win32).
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try:
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self.kernel.kill()
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except OSError as e:
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# In Windows, we will get an Access Denied error if the process
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# has already terminated. Ignore it.
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if sys.platform == 'win32':
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if e.winerror != 5:
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raise
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# On Unix, we may get an ESRCH error if the process has already
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# terminated. Ignore it.
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else:
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from errno import ESRCH
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if e.errno != ESRCH:
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raise
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# Block until the kernel terminates.
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self.kernel.wait()
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self.kernel = None
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else:
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raise RuntimeError("Cannot kill kernel. No kernel is running!")
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def interrupt_kernel(self):
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"""Interrupts the kernel by sending it a signal.
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Unlike ``signal_kernel``, this operation is well supported on all
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platforms.
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"""
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if self.has_kernel:
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if sys.platform == 'win32':
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from .zmq.parentpoller import ParentPollerWindows as Poller
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Poller.send_interrupt(self.kernel.win32_interrupt_event)
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else:
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self.kernel.send_signal(signal.SIGINT)
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else:
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raise RuntimeError("Cannot interrupt kernel. No kernel is running!")
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def signal_kernel(self, signum):
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"""Sends a signal to the kernel.
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Note that since only SIGTERM is supported on Windows, this function is
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only useful on Unix systems.
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"""
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if self.has_kernel:
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self.kernel.send_signal(signum)
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else:
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raise RuntimeError("Cannot signal kernel. No kernel is running!")
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def is_alive(self):
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"""Is the kernel process still running?"""
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if self.has_kernel:
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if self.kernel.poll() is None:
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return True
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else:
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return False
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else:
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# we don't have a kernel
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return False
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KernelManagerABC.register(KernelManager)
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def start_new_kernel(startup_timeout=60, kernel_name='python', **kwargs):
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"""Start a new kernel, and return its Manager and Client"""
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km = KernelManager(kernel_name=kernel_name)
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km.start_kernel(**kwargs)
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kc = km.client()
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kc.start_channels()
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kc.wait_for_ready()
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return km, kc
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@contextmanager
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def run_kernel(**kwargs):
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"""Context manager to create a kernel in a subprocess.
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The kernel is shut down when the context exits.
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Returns
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-------
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kernel_client: connected KernelClient instance
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"""
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km, kc = start_new_kernel(**kwargs)
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try:
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yield kc
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finally:
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kc.stop_channels()
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km.shutdown_kernel(now=True)
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