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"""KernelStarter class that intercepts Control Queue messages, and handles process management.
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Authors:
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* Min RK
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"""
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#-----------------------------------------------------------------------------
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# Copyright (C) 2010-2011 The IPython Development Team
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#
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# Distributed under the terms of the BSD License. The full license is in
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# the file COPYING, distributed as part of this software.
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#-----------------------------------------------------------------------------
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from zmq.eventloop import ioloop
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from IPython.zmq.session import Session
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class KernelStarter(object):
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"""Object for resetting/killing the Kernel."""
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def __init__(self, session, upstream, downstream, *kernel_args, **kernel_kwargs):
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self.session = session
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self.upstream = upstream
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self.downstream = downstream
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self.kernel_args = kernel_args
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self.kernel_kwargs = kernel_kwargs
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self.handlers = {}
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for method in 'shutdown_request shutdown_reply'.split():
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self.handlers[method] = getattr(self, method)
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def start(self):
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self.upstream.on_recv(self.dispatch_request)
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self.downstream.on_recv(self.dispatch_reply)
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#--------------------------------------------------------------------------
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# Dispatch methods
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#--------------------------------------------------------------------------
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def dispatch_request(self, raw_msg):
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idents, msg = self.session.feed_identities()
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try:
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msg = self.session.unpack_message(msg, content=False)
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except:
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print ("bad msg: %s"%msg)
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msgtype = msg['msg_type']
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handler = self.handlers.get(msgtype, None)
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if handler is None:
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self.downstream.send_multipart(raw_msg, copy=False)
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else:
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handler(msg)
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def dispatch_reply(self, raw_msg):
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idents, msg = self.session.feed_identities()
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try:
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msg = self.session.unpack_message(msg, content=False)
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except:
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print ("bad msg: %s"%msg)
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msgtype = msg['msg_type']
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handler = self.handlers.get(msgtype, None)
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if handler is None:
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self.upstream.send_multipart(raw_msg, copy=False)
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else:
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handler(msg)
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#--------------------------------------------------------------------------
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# Handlers
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#--------------------------------------------------------------------------
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def shutdown_request(self, msg):
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""""""
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self.downstream.send_multipart(msg)
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#--------------------------------------------------------------------------
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# Kernel process management methods, from KernelManager:
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#--------------------------------------------------------------------------
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def _check_local(addr):
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if isinstance(addr, tuple):
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addr = addr[0]
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return addr in LOCAL_IPS
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def start_kernel(self, **kw):
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"""Starts a kernel process and configures the manager to use it.
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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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ipython : bool, optional (default True)
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Whether to use an IPython kernel instead of a plain Python kernel.
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"""
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self.kernel = Process(target=make_kernel, args=self.kernel_args,
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kwargs=self.kernel_kwargs)
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def shutdown_kernel(self, restart=False):
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""" Attempts to the stop the kernel process cleanly. If the kernel
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cannot be stopped, it is killed, if possible.
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"""
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# FIXME: Shutdown does not work on Windows due to ZMQ errors!
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if sys.platform == 'win32':
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self.kill_kernel()
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return
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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.xreq_channel.shutdown(restart=restart)
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for i in range(10):
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if self.is_alive:
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time.sleep(0.1)
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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 restart_kernel(self, now=False):
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"""Restarts a kernel with the same arguments that were used to launch
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it. If the old kernel was launched with random ports, the same ports
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will be used for the new kernel.
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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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"""
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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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if self.has_kernel:
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if now:
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self.kill_kernel()
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else:
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self.shutdown_kernel(restart=True)
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self.start_kernel(**self._launch_args)
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# FIXME: Messages get dropped in Windows due to probable ZMQ bug
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# unless there is some delay here.
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if sys.platform == 'win32':
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time.sleep(0.2)
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@property
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def has_kernel(self):
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"""Returns whether a kernel process has been specified for the kernel
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manager.
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"""
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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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if self.has_kernel:
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# Pause the heart beat channel if it exists.
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if self._hb_channel is not None:
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self._hb_channel.pause()
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# Attempt to kill the kernel.
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try:
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self.kernel.kill()
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except OSError, 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 not (sys.platform == 'win32' and e.winerror == 5):
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raise
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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. Unlike ``signal_kernel``, this operation is
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well supported on all 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 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. Note that since only SIGTERM is
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supported on Windows, this function is 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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@property
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def is_alive(self):
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"""Is the kernel process still running?"""
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# FIXME: not using a heartbeat means this method is broken for any
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# remote kernel, it's only capable of handling local kernels.
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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 didn't start the kernel with this KernelManager so we don't
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# know if it is running. We should use a heartbeat for this case.
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return True
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def make_starter(up_addr, down_addr, *args, **kwargs):
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"""entry point function for launching a kernelstarter in a subprocess"""
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loop = ioloop.IOLoop.instance()
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ctx = zmq.Context()
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session = Session()
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upstream = zmqstream.ZMQStream(ctx.socket(zmq.XREQ),loop)
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upstream.connect(up_addr)
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downstream = zmqstream.ZMQStream(ctx.socket(zmq.XREQ),loop)
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downstream.connect(down_addr)
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starter = KernelStarter(session, upstream, downstream, *args, **kwargs)
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starter.start()
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loop.start()
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