#!/usr/bin/env python """A simple interactive kernel that talks to a frontend over 0MQ. Things to do: * Implement `set_parent` logic. Right before doing exec, the Kernel should call set_parent on all the PUB objects with the message about to be executed. * Implement random port and security key logic. * Implement control messages. * Implement event loop and poll version. """ #----------------------------------------------------------------------------- # Imports #----------------------------------------------------------------------------- from __future__ import print_function # Standard library imports import __builtin__ import atexit import sys import time import traceback import logging import uuid from datetime import datetime from signal import ( signal, getsignal, default_int_handler, SIGINT, SIG_IGN ) # System library imports import zmq from zmq.eventloop import ioloop from zmq.eventloop.zmqstream import ZMQStream # Local imports from IPython.config.configurable import Configurable from IPython.config.application import boolean_flag, catch_config_error from IPython.core.application import ProfileDir from IPython.core.error import StdinNotImplementedError from IPython.core.shellapp import ( InteractiveShellApp, shell_flags, shell_aliases ) from IPython.utils import io from IPython.utils import py3compat from IPython.utils.frame import extract_module_locals from IPython.utils.jsonutil import json_clean from IPython.utils.traitlets import ( Any, Instance, Float, Dict, CaselessStrEnum, List, Set, Integer, Unicode, Type ) from entry_point import base_launch_kernel from kernelapp import KernelApp, kernel_flags, kernel_aliases from serialize import serialize_object, unpack_apply_message from session import Session, Message from zmqshell import ZMQInteractiveShell #----------------------------------------------------------------------------- # Main kernel class #----------------------------------------------------------------------------- class Kernel(Configurable): #--------------------------------------------------------------------------- # Kernel interface #--------------------------------------------------------------------------- # attribute to override with a GUI eventloop = Any(None) def _eventloop_changed(self, name, old, new): """schedule call to eventloop from IOLoop""" loop = ioloop.IOLoop.instance() loop.add_timeout(time.time()+0.1, self.enter_eventloop) shell = Instance('IPython.core.interactiveshell.InteractiveShellABC') shell_class = Type(ZMQInteractiveShell) session = Instance(Session) profile_dir = Instance('IPython.core.profiledir.ProfileDir') shell_streams = List() control_stream = Instance(ZMQStream) iopub_socket = Instance(zmq.Socket) stdin_socket = Instance(zmq.Socket) log = Instance(logging.Logger) user_module = Any() def _user_module_changed(self, name, old, new): if self.shell is not None: self.shell.user_module = new user_ns = Dict(default_value=None) def _user_ns_changed(self, name, old, new): if self.shell is not None: self.shell.user_ns = new self.shell.init_user_ns() # identities: int_id = Integer(-1) ident = Unicode() def _ident_default(self): return unicode(uuid.uuid4()) # Private interface # Time to sleep after flushing the stdout/err buffers in each execute # cycle. While this introduces a hard limit on the minimal latency of the # execute cycle, it helps prevent output synchronization problems for # clients. # Units are in seconds. The minimum zmq latency on local host is probably # ~150 microseconds, set this to 500us for now. We may need to increase it # a little if it's not enough after more interactive testing. _execute_sleep = Float(0.0005, config=True) # Frequency of the kernel's event loop. # Units are in seconds, kernel subclasses for GUI toolkits may need to # adapt to milliseconds. _poll_interval = Float(0.05, config=True) # If the shutdown was requested over the network, we leave here the # necessary reply message so it can be sent by our registered atexit # handler. This ensures that the reply is only sent to clients truly at # the end of our shutdown process (which happens after the underlying # IPython shell's own shutdown). _shutdown_message = None # This is a dict of port number that the kernel is listening on. It is set # by record_ports and used by connect_request. _recorded_ports = Dict() # set of aborted msg_ids aborted = Set() def __init__(self, **kwargs): super(Kernel, self).__init__(**kwargs) # Initialize the InteractiveShell subclass self.shell = self.shell_class.instance(config=self.config, profile_dir = self.profile_dir, user_module = self.user_module, user_ns = self.user_ns, ) self.shell.displayhook.session = self.session self.shell.displayhook.pub_socket = self.iopub_socket self.shell.displayhook.topic = self._topic('pyout') self.shell.display_pub.session = self.session self.shell.display_pub.pub_socket = self.iopub_socket self.shell.data_pub.session = self.session self.shell.data_pub.pub_socket = self.iopub_socket # TMP - hack while developing self.shell._reply_content = None # Build dict of handlers for message types msg_types = [ 'execute_request', 'complete_request', 'object_info_request', 'history_request', 'connect_request', 'shutdown_request', 'apply_request', ] self.shell_handlers = {} for msg_type in msg_types: self.shell_handlers[msg_type] = getattr(self, msg_type) control_msg_types = msg_types + [ 'clear_request', 'abort_request' ] self.control_handlers = {} for msg_type in control_msg_types: self.control_handlers[msg_type] = getattr(self, msg_type) def dispatch_control(self, msg): """dispatch control requests""" idents,msg = self.session.feed_identities(msg, copy=False) try: msg = self.session.unserialize(msg, content=True, copy=False) except: self.log.error("Invalid Control Message", exc_info=True) return self.log.debug("Control received: %s", msg) header = msg['header'] msg_id = header['msg_id'] msg_type = header['msg_type'] handler = self.control_handlers.get(msg_type, None) if handler is None: self.log.error("UNKNOWN CONTROL MESSAGE TYPE: %r", msg_type) else: try: handler(self.control_stream, idents, msg) except Exception: self.log.error("Exception in control handler:", exc_info=True) def dispatch_shell(self, stream, msg): """dispatch shell requests""" # flush control requests first if self.control_stream: self.control_stream.flush() idents,msg = self.session.feed_identities(msg, copy=False) try: msg = self.session.unserialize(msg, content=True, copy=False) except: self.log.error("Invalid Message", exc_info=True) return header = msg['header'] msg_id = header['msg_id'] msg_type = msg['header']['msg_type'] # Print some info about this message and leave a '--->' marker, so it's # easier to trace visually the message chain when debugging. Each # handler prints its message at the end. self.log.debug('\n*** MESSAGE TYPE:%s***', msg_type) self.log.debug(' Content: %s\n --->\n ', msg['content']) if msg_id in self.aborted: self.aborted.remove(msg_id) # is it safe to assume a msg_id will not be resubmitted? reply_type = msg_type.split('_')[0] + '_reply' status = {'status' : 'aborted'} md = {'engine' : self.ident} md.update(status) reply_msg = self.session.send(stream, reply_type, metadata=md, content=status, parent=msg, ident=idents) return handler = self.shell_handlers.get(msg_type, None) if handler is None: self.log.error("UNKNOWN MESSAGE TYPE: %r", msg_type) else: # ensure default_int_handler during handler call sig = signal(SIGINT, default_int_handler) try: handler(stream, idents, msg) except Exception: self.log.error("Exception in message handler:", exc_info=True) finally: signal(SIGINT, sig) def enter_eventloop(self): """enter eventloop""" self.log.info("entering eventloop") # restore default_int_handler signal(SIGINT, default_int_handler) while self.eventloop is not None: try: self.eventloop(self) except KeyboardInterrupt: # Ctrl-C shouldn't crash the kernel self.log.error("KeyboardInterrupt caught in kernel") continue else: # eventloop exited cleanly, this means we should stop (right?) self.eventloop = None break self.log.info("exiting eventloop") def start(self): """register dispatchers for streams""" self.shell.exit_now = False if self.control_stream: self.control_stream.on_recv(self.dispatch_control, copy=False) def make_dispatcher(stream): def dispatcher(msg): return self.dispatch_shell(stream, msg) return dispatcher for s in self.shell_streams: s.on_recv(make_dispatcher(s), copy=False) def do_one_iteration(self): """step eventloop just once""" if self.control_stream: self.control_stream.flush() for stream in self.shell_streams: # handle at most one request per iteration stream.flush(zmq.POLLIN, 1) stream.flush(zmq.POLLOUT) def record_ports(self, ports): """Record the ports that this kernel is using. The creator of the Kernel instance must call this methods if they want the :meth:`connect_request` method to return the port numbers. """ self._recorded_ports = ports #--------------------------------------------------------------------------- # Kernel request handlers #--------------------------------------------------------------------------- def _make_metadata(self, other=None): """init metadata dict, for execute/apply_reply""" new_md = { 'dependencies_met' : True, 'engine' : self.ident, 'started': datetime.now(), } if other: new_md.update(other) return new_md def _publish_pyin(self, code, parent, execution_count): """Publish the code request on the pyin stream.""" self.session.send(self.iopub_socket, u'pyin', {u'code':code, u'execution_count': execution_count}, parent=parent, ident=self._topic('pyin') ) def _publish_status(self, status, parent=None): """send status (busy/idle) on IOPub""" self.session.send(self.iopub_socket, u'status', {u'execution_state': status}, parent=parent, ident=self._topic('status'), ) def execute_request(self, stream, ident, parent): """handle an execute_request""" self._publish_status(u'busy', parent) try: content = parent[u'content'] code = content[u'code'] silent = content[u'silent'] store_history = content.get(u'store_history', not silent) except: self.log.error("Got bad msg: ") self.log.error("%s", parent) return md = self._make_metadata(parent['metadata']) shell = self.shell # we'll need this a lot here # Replace raw_input. Note that is not sufficient to replace # raw_input in the user namespace. if content.get('allow_stdin', False): raw_input = lambda prompt='': self._raw_input(prompt, ident, parent) else: raw_input = lambda prompt='' : self._no_raw_input() if py3compat.PY3: __builtin__.input = raw_input else: __builtin__.raw_input = raw_input # Set the parent message of the display hook and out streams. shell.displayhook.set_parent(parent) shell.display_pub.set_parent(parent) shell.data_pub.set_parent(parent) sys.stdout.set_parent(parent) sys.stderr.set_parent(parent) # Re-broadcast our input for the benefit of listening clients, and # start computing output if not silent: self._publish_pyin(code, parent, shell.execution_count) reply_content = {} try: # FIXME: the shell calls the exception handler itself. shell.run_cell(code, store_history=store_history, silent=silent) except: status = u'error' # FIXME: this code right now isn't being used yet by default, # because the run_cell() call above directly fires off exception # reporting. This code, therefore, is only active in the scenario # where runlines itself has an unhandled exception. We need to # uniformize this, for all exception construction to come from a # single location in the codbase. etype, evalue, tb = sys.exc_info() tb_list = traceback.format_exception(etype, evalue, tb) reply_content.update(shell._showtraceback(etype, evalue, tb_list)) else: status = u'ok' reply_content[u'status'] = status # Return the execution counter so clients can display prompts reply_content['execution_count'] = shell.execution_count - 1 # FIXME - fish exception info out of shell, possibly left there by # runlines. We'll need to clean up this logic later. if shell._reply_content is not None: reply_content.update(shell._reply_content) e_info = dict(engine_uuid=self.ident, engine_id=self.int_id, method='execute') reply_content['engine_info'] = e_info # reset after use shell._reply_content = None # At this point, we can tell whether the main code execution succeeded # or not. If it did, we proceed to evaluate user_variables/expressions if reply_content['status'] == 'ok': reply_content[u'user_variables'] = \ shell.user_variables(content.get(u'user_variables', [])) reply_content[u'user_expressions'] = \ shell.user_expressions(content.get(u'user_expressions', {})) else: # If there was an error, don't even try to compute variables or # expressions reply_content[u'user_variables'] = {} reply_content[u'user_expressions'] = {} # Payloads should be retrieved regardless of outcome, so we can both # recover partial output (that could have been generated early in a # block, before an error) and clear the payload system always. reply_content[u'payload'] = shell.payload_manager.read_payload() # Be agressive about clearing the payload because we don't want # it to sit in memory until the next execute_request comes in. shell.payload_manager.clear_payload() # Flush output before sending the reply. sys.stdout.flush() sys.stderr.flush() # FIXME: on rare occasions, the flush doesn't seem to make it to the # clients... This seems to mitigate the problem, but we definitely need # to better understand what's going on. if self._execute_sleep: time.sleep(self._execute_sleep) # Send the reply. reply_content = json_clean(reply_content) md['status'] = reply_content['status'] if reply_content['status'] == 'error' and \ reply_content['ename'] == 'UnmetDependency': md['dependencies_met'] = False reply_msg = self.session.send(stream, u'execute_reply', reply_content, parent, metadata=md, ident=ident) self.log.debug("%s", reply_msg) if not silent and reply_msg['content']['status'] == u'error': self._abort_queues() self._publish_status(u'idle', parent) def complete_request(self, stream, ident, parent): txt, matches = self._complete(parent) matches = {'matches' : matches, 'matched_text' : txt, 'status' : 'ok'} matches = json_clean(matches) completion_msg = self.session.send(stream, 'complete_reply', matches, parent, ident) self.log.debug("%s", completion_msg) def object_info_request(self, stream, ident, parent): content = parent['content'] object_info = self.shell.object_inspect(content['oname'], detail_level = content.get('detail_level', 0) ) # Before we send this object over, we scrub it for JSON usage oinfo = json_clean(object_info) msg = self.session.send(stream, 'object_info_reply', oinfo, parent, ident) self.log.debug("%s", msg) def history_request(self, stream, ident, parent): # We need to pull these out, as passing **kwargs doesn't work with # unicode keys before Python 2.6.5. hist_access_type = parent['content']['hist_access_type'] raw = parent['content']['raw'] output = parent['content']['output'] if hist_access_type == 'tail': n = parent['content']['n'] hist = self.shell.history_manager.get_tail(n, raw=raw, output=output, include_latest=True) elif hist_access_type == 'range': session = parent['content']['session'] start = parent['content']['start'] stop = parent['content']['stop'] hist = self.shell.history_manager.get_range(session, start, stop, raw=raw, output=output) elif hist_access_type == 'search': pattern = parent['content']['pattern'] hist = self.shell.history_manager.search(pattern, raw=raw, output=output) else: hist = [] hist = list(hist) content = {'history' : hist} content = json_clean(content) msg = self.session.send(stream, 'history_reply', content, parent, ident) self.log.debug("Sending history reply with %i entries", len(hist)) def connect_request(self, stream, ident, parent): if self._recorded_ports is not None: content = self._recorded_ports.copy() else: content = {} msg = self.session.send(stream, 'connect_reply', content, parent, ident) self.log.debug("%s", msg) def shutdown_request(self, stream, ident, parent): self.shell.exit_now = True content = dict(status='ok') content.update(parent['content']) self.session.send(stream, u'shutdown_reply', content, parent, ident=ident) # same content, but different msg_id for broadcasting on IOPub self._shutdown_message = self.session.msg(u'shutdown_reply', content, parent ) self._at_shutdown() # call sys.exit after a short delay loop = ioloop.IOLoop.instance() loop.add_timeout(time.time()+0.1, loop.stop) #--------------------------------------------------------------------------- # Engine methods #--------------------------------------------------------------------------- def apply_request(self, stream, ident, parent): try: content = parent[u'content'] bufs = parent[u'buffers'] msg_id = parent['header']['msg_id'] except: self.log.error("Got bad msg: %s", parent, exc_info=True) return self._publish_status(u'busy', parent) # Set the parent message of the display hook and out streams. shell = self.shell shell.displayhook.set_parent(parent) shell.display_pub.set_parent(parent) shell.data_pub.set_parent(parent) sys.stdout.set_parent(parent) sys.stderr.set_parent(parent) # pyin_msg = self.session.msg(u'pyin',{u'code':code}, parent=parent) # self.iopub_socket.send(pyin_msg) # self.session.send(self.iopub_socket, u'pyin', {u'code':code},parent=parent) md = self._make_metadata(parent['metadata']) try: working = shell.user_ns prefix = "_"+str(msg_id).replace("-","")+"_" f,args,kwargs = unpack_apply_message(bufs, working, copy=False) fname = getattr(f, '__name__', 'f') fname = prefix+"f" argname = prefix+"args" kwargname = prefix+"kwargs" resultname = prefix+"result" ns = { fname : f, argname : args, kwargname : kwargs , resultname : None } # print ns working.update(ns) code = "%s = %s(*%s,**%s)" % (resultname, fname, argname, kwargname) try: exec code in shell.user_global_ns, shell.user_ns result = working.get(resultname) finally: for key in ns.iterkeys(): working.pop(key) result_buf = serialize_object(result, buffer_threshold=self.session.buffer_threshold, item_threshold=self.session.item_threshold, ) except: # invoke IPython traceback formatting shell.showtraceback() # FIXME - fish exception info out of shell, possibly left there by # run_code. We'll need to clean up this logic later. reply_content = {} if shell._reply_content is not None: reply_content.update(shell._reply_content) e_info = dict(engine_uuid=self.ident, engine_id=self.int_id, method='apply') reply_content['engine_info'] = e_info # reset after use shell._reply_content = None self.session.send(self.iopub_socket, u'pyerr', reply_content, parent=parent, ident=self._topic('pyerr')) result_buf = [] if reply_content['ename'] == 'UnmetDependency': md['dependencies_met'] = False else: reply_content = {'status' : 'ok'} # put 'ok'/'error' status in header, for scheduler introspection: md['status'] = reply_content['status'] # flush i/o sys.stdout.flush() sys.stderr.flush() reply_msg = self.session.send(stream, u'apply_reply', reply_content, parent=parent, ident=ident,buffers=result_buf, metadata=md) self._publish_status(u'idle', parent) #--------------------------------------------------------------------------- # Control messages #--------------------------------------------------------------------------- def abort_request(self, stream, ident, parent): """abort a specifig msg by id""" msg_ids = parent['content'].get('msg_ids', None) if isinstance(msg_ids, basestring): msg_ids = [msg_ids] if not msg_ids: self.abort_queues() for mid in msg_ids: self.aborted.add(str(mid)) content = dict(status='ok') reply_msg = self.session.send(stream, 'abort_reply', content=content, parent=parent, ident=ident) self.log.debug("%s", reply_msg) def clear_request(self, stream, idents, parent): """Clear our namespace.""" self.shell.reset(False) msg = self.session.send(stream, 'clear_reply', ident=idents, parent=parent, content = dict(status='ok')) #--------------------------------------------------------------------------- # Protected interface #--------------------------------------------------------------------------- def _wrap_exception(self, method=None): # import here, because _wrap_exception is only used in parallel, # and parallel has higher min pyzmq version from IPython.parallel.error import wrap_exception e_info = dict(engine_uuid=self.ident, engine_id=self.int_id, method=method) content = wrap_exception(e_info) return content def _topic(self, topic): """prefixed topic for IOPub messages""" if self.int_id >= 0: base = "engine.%i" % self.int_id else: base = "kernel.%s" % self.ident return py3compat.cast_bytes("%s.%s" % (base, topic)) def _abort_queues(self): for stream in self.shell_streams: if stream: self._abort_queue(stream) def _abort_queue(self, stream): poller = zmq.Poller() poller.register(stream.socket, zmq.POLLIN) while True: idents,msg = self.session.recv(stream, zmq.NOBLOCK, content=True) if msg is None: return self.log.info("Aborting:") self.log.info("%s", msg) msg_type = msg['header']['msg_type'] reply_type = msg_type.split('_')[0] + '_reply' status = {'status' : 'aborted'} md = {'engine' : self.ident} md.update(status) reply_msg = self.session.send(stream, reply_type, metadata=md, content=status, parent=msg, ident=idents) self.log.debug("%s", reply_msg) # We need to wait a bit for requests to come in. This can probably # be set shorter for true asynchronous clients. poller.poll(50) def _no_raw_input(self): """Raise StdinNotImplentedError if active frontend doesn't support stdin.""" raise StdinNotImplementedError("raw_input was called, but this " "frontend does not support stdin.") def _raw_input(self, prompt, ident, parent): # Flush output before making the request. sys.stderr.flush() sys.stdout.flush() # Send the input request. content = json_clean(dict(prompt=prompt)) self.session.send(self.stdin_socket, u'input_request', content, parent, ident=ident) # Await a response. while True: try: ident, reply = self.session.recv(self.stdin_socket, 0) except Exception: self.log.warn("Invalid Message:", exc_info=True) else: break try: value = reply['content']['value'] except: self.log.error("Got bad raw_input reply: ") self.log.error("%s", parent) value = '' if value == '\x04': # EOF raise EOFError return value def _complete(self, msg): c = msg['content'] try: cpos = int(c['cursor_pos']) except: # If we don't get something that we can convert to an integer, at # least attempt the completion guessing the cursor is at the end of # the text, if there's any, and otherwise of the line cpos = len(c['text']) if cpos==0: cpos = len(c['line']) return self.shell.complete(c['text'], c['line'], cpos) def _at_shutdown(self): """Actions taken at shutdown by the kernel, called by python's atexit. """ # io.rprint("Kernel at_shutdown") # dbg if self._shutdown_message is not None: self.session.send(self.iopub_socket, self._shutdown_message, ident=self._topic('shutdown')) self.log.debug("%s", self._shutdown_message) [ s.flush(zmq.POLLOUT) for s in self.shell_streams ] #----------------------------------------------------------------------------- # Aliases and Flags for the IPKernelApp #----------------------------------------------------------------------------- flags = dict(kernel_flags) flags.update(shell_flags) addflag = lambda *args: flags.update(boolean_flag(*args)) flags['pylab'] = ( {'IPKernelApp' : {'pylab' : 'auto'}}, """Pre-load matplotlib and numpy for interactive use with the default matplotlib backend.""" ) aliases = dict(kernel_aliases) aliases.update(shell_aliases) #----------------------------------------------------------------------------- # The IPKernelApp class #----------------------------------------------------------------------------- class IPKernelApp(KernelApp, InteractiveShellApp): name = 'ipkernel' aliases = Dict(aliases) flags = Dict(flags) classes = [Kernel, ZMQInteractiveShell, ProfileDir, Session] @catch_config_error def initialize(self, argv=None): super(IPKernelApp, self).initialize(argv) self.init_path() self.init_shell() self.init_gui_pylab() self.init_extensions() self.init_code() def init_kernel(self): shell_stream = ZMQStream(self.shell_socket) kernel = Kernel(config=self.config, session=self.session, shell_streams=[shell_stream], iopub_socket=self.iopub_socket, stdin_socket=self.stdin_socket, log=self.log, profile_dir=self.profile_dir, ) self.kernel = kernel kernel.record_ports(self.ports) shell = kernel.shell def init_gui_pylab(self): """Enable GUI event loop integration, taking pylab into account.""" # Provide a wrapper for :meth:`InteractiveShellApp.init_gui_pylab` # to ensure that any exception is printed straight to stderr. # Normally _showtraceback associates the reply with an execution, # which means frontends will never draw it, as this exception # is not associated with any execute request. shell = self.shell _showtraceback = shell._showtraceback try: # replace pyerr-sending traceback with stderr def print_tb(etype, evalue, stb): print ("GUI event loop or pylab initialization failed", file=io.stderr) print (shell.InteractiveTB.stb2text(stb), file=io.stderr) shell._showtraceback = print_tb InteractiveShellApp.init_gui_pylab(self) finally: shell._showtraceback = _showtraceback def init_shell(self): self.shell = self.kernel.shell self.shell.configurables.append(self) #----------------------------------------------------------------------------- # Kernel main and launch functions #----------------------------------------------------------------------------- def launch_kernel(*args, **kwargs): """Launches a localhost IPython kernel, binding to the specified ports. This function simply calls entry_point.base_launch_kernel with the right first command to start an ipkernel. See base_launch_kernel for arguments. Returns ------- A tuple of form: (kernel_process, shell_port, iopub_port, stdin_port, hb_port) where kernel_process is a Popen object and the ports are integers. """ return base_launch_kernel('from IPython.zmq.ipkernel import main; main()', *args, **kwargs) def embed_kernel(module=None, local_ns=None, **kwargs): """Embed and start an IPython kernel in a given scope. Parameters ---------- module : ModuleType, optional The module to load into IPython globals (default: caller) local_ns : dict, optional The namespace to load into IPython user namespace (default: caller) kwargs : various, optional Further keyword args are relayed to the KernelApp constructor, allowing configuration of the Kernel. Will only have an effect on the first embed_kernel call for a given process. """ # get the app if it exists, or set it up if it doesn't if IPKernelApp.initialized(): app = IPKernelApp.instance() else: app = IPKernelApp.instance(**kwargs) app.initialize([]) # Undo unnecessary sys module mangling from init_sys_modules. # This would not be necessary if we could prevent it # in the first place by using a different InteractiveShell # subclass, as in the regular embed case. main = app.kernel.shell._orig_sys_modules_main_mod if main is not None: sys.modules[app.kernel.shell._orig_sys_modules_main_name] = main # load the calling scope if not given (caller_module, caller_locals) = extract_module_locals(1) if module is None: module = caller_module if local_ns is None: local_ns = caller_locals app.kernel.user_module = module app.kernel.user_ns = local_ns app.shell.set_completer_frame() app.start() def main(): """Run an IPKernel as an application""" app = IPKernelApp.instance() app.initialize() app.start() if __name__ == '__main__': main()