"""Base classes to manage the interaction with a running kernel. TODO * Create logger to handle debugging and console messages. """ #----------------------------------------------------------------------------- # Copyright (C) 2008-2010 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 #----------------------------------------------------------------------------- # Standard library imports. import errno import json from Queue import Queue, Empty from subprocess import Popen import os import signal import sys from threading import Thread import time # System library imports. import zmq from zmq import POLLIN, POLLOUT, POLLERR from zmq.eventloop import ioloop # Local imports. from IPython.config.loader import Config from IPython.utils.localinterfaces import LOCALHOST, LOCAL_IPS from IPython.utils.traitlets import ( HasTraits, Any, Instance, Type, Unicode, Int, Bool ) from IPython.utils.py3compat import str_to_bytes from IPython.zmq.entry_point import write_connection_file from session import Session #----------------------------------------------------------------------------- # Constants and exceptions #----------------------------------------------------------------------------- class InvalidPortNumber(Exception): pass #----------------------------------------------------------------------------- # Utility functions #----------------------------------------------------------------------------- # some utilities to validate message structure, these might get moved elsewhere # if they prove to have more generic utility def validate_string_list(lst): """Validate that the input is a list of strings. Raises ValueError if not.""" if not isinstance(lst, list): raise ValueError('input %r must be a list' % lst) for x in lst: if not isinstance(x, basestring): raise ValueError('element %r in list must be a string' % x) def validate_string_dict(dct): """Validate that the input is a dict with string keys and values. Raises ValueError if not.""" for k,v in dct.iteritems(): if not isinstance(k, basestring): raise ValueError('key %r in dict must be a string' % k) if not isinstance(v, basestring): raise ValueError('value %r in dict must be a string' % v) #----------------------------------------------------------------------------- # ZMQ Socket Channel classes #----------------------------------------------------------------------------- class ZMQSocketChannel(Thread): """The base class for the channels that use ZMQ sockets. """ context = None session = None socket = None ioloop = None iostate = None _address = None def __init__(self, context, session, address): """Create a channel Parameters ---------- context : :class:`zmq.Context` The ZMQ context to use. session : :class:`session.Session` The session to use. address : tuple Standard (ip, port) tuple that the kernel is listening on. """ super(ZMQSocketChannel, self).__init__() self.daemon = True self.context = context self.session = session if address[1] == 0: message = 'The port number for a channel cannot be 0.' raise InvalidPortNumber(message) self._address = address def _run_loop(self): """Run my loop, ignoring EINTR events in the poller""" while True: try: self.ioloop.start() except zmq.ZMQError as e: if e.errno == errno.EINTR: continue else: raise else: break def stop(self): """Stop the channel's activity. This calls :method:`Thread.join` and returns when the thread terminates. :class:`RuntimeError` will be raised if :method:`self.start` is called again. """ self.join() @property def address(self): """Get the channel's address as an (ip, port) tuple. By the default, the address is (localhost, 0), where 0 means a random port. """ return self._address def add_io_state(self, state): """Add IO state to the eventloop. Parameters ---------- state : zmq.POLLIN|zmq.POLLOUT|zmq.POLLERR The IO state flag to set. This is thread safe as it uses the thread safe IOLoop.add_callback. """ def add_io_state_callback(): if not self.iostate & state: self.iostate = self.iostate | state self.ioloop.update_handler(self.socket, self.iostate) self.ioloop.add_callback(add_io_state_callback) def drop_io_state(self, state): """Drop IO state from the eventloop. Parameters ---------- state : zmq.POLLIN|zmq.POLLOUT|zmq.POLLERR The IO state flag to set. This is thread safe as it uses the thread safe IOLoop.add_callback. """ def drop_io_state_callback(): if self.iostate & state: self.iostate = self.iostate & (~state) self.ioloop.update_handler(self.socket, self.iostate) self.ioloop.add_callback(drop_io_state_callback) class ShellSocketChannel(ZMQSocketChannel): """The XREQ channel for issues request/replies to the kernel. """ command_queue = None # flag for whether execute requests should be allowed to call raw_input: allow_stdin = True def __init__(self, context, session, address): super(ShellSocketChannel, self).__init__(context, session, address) self.command_queue = Queue() self.ioloop = ioloop.IOLoop() def run(self): """The thread's main activity. Call start() instead.""" self.socket = self.context.socket(zmq.DEALER) self.socket.setsockopt(zmq.IDENTITY, self.session.bsession) self.socket.connect('tcp://%s:%i' % self.address) self.iostate = POLLERR|POLLIN self.ioloop.add_handler(self.socket, self._handle_events, self.iostate) self._run_loop() def stop(self): self.ioloop.stop() super(ShellSocketChannel, self).stop() def call_handlers(self, msg): """This method is called in the ioloop thread when a message arrives. Subclasses should override this method to handle incoming messages. It is important to remember that this method is called in the thread so that some logic must be done to ensure that the application leve handlers are called in the application thread. """ raise NotImplementedError('call_handlers must be defined in a subclass.') def execute(self, code, silent=False, user_variables=None, user_expressions=None, allow_stdin=None): """Execute code in the kernel. Parameters ---------- code : str A string of Python code. silent : bool, optional (default False) If set, the kernel will execute the code as quietly possible. user_variables : list, optional A list of variable names to pull from the user's namespace. They will come back as a dict with these names as keys and their :func:`repr` as values. user_expressions : dict, optional A dict with string keys and to pull from the user's namespace. They will come back as a dict with these names as keys and their :func:`repr` as values. allow_stdin : bool, optional Flag for A dict with string keys and to pull from the user's namespace. They will come back as a dict with these names as keys and their :func:`repr` as values. Returns ------- The msg_id of the message sent. """ if user_variables is None: user_variables = [] if user_expressions is None: user_expressions = {} if allow_stdin is None: allow_stdin = self.allow_stdin # Don't waste network traffic if inputs are invalid if not isinstance(code, basestring): raise ValueError('code %r must be a string' % code) validate_string_list(user_variables) validate_string_dict(user_expressions) # Create class for content/msg creation. Related to, but possibly # not in Session. content = dict(code=code, silent=silent, user_variables=user_variables, user_expressions=user_expressions, allow_stdin=allow_stdin, ) msg = self.session.msg('execute_request', content) self._queue_request(msg) return msg['header']['msg_id'] def complete(self, text, line, cursor_pos, block=None): """Tab complete text in the kernel's namespace. Parameters ---------- text : str The text to complete. line : str The full line of text that is the surrounding context for the text to complete. cursor_pos : int The position of the cursor in the line where the completion was requested. block : str, optional The full block of code in which the completion is being requested. Returns ------- The msg_id of the message sent. """ content = dict(text=text, line=line, block=block, cursor_pos=cursor_pos) msg = self.session.msg('complete_request', content) self._queue_request(msg) return msg['header']['msg_id'] def object_info(self, oname): """Get metadata information about an object. Parameters ---------- oname : str A string specifying the object name. Returns ------- The msg_id of the message sent. """ content = dict(oname=oname) msg = self.session.msg('object_info_request', content) self._queue_request(msg) return msg['header']['msg_id'] def history(self, raw=True, output=False, hist_access_type='range', **kwargs): """Get entries from the history list. Parameters ---------- raw : bool If True, return the raw input. output : bool If True, then return the output as well. hist_access_type : str 'range' (fill in session, start and stop params), 'tail' (fill in n) or 'search' (fill in pattern param). session : int For a range request, the session from which to get lines. Session numbers are positive integers; negative ones count back from the current session. start : int The first line number of a history range. stop : int The final (excluded) line number of a history range. n : int The number of lines of history to get for a tail request. pattern : str The glob-syntax pattern for a search request. Returns ------- The msg_id of the message sent. """ content = dict(raw=raw, output=output, hist_access_type=hist_access_type, **kwargs) msg = self.session.msg('history_request', content) self._queue_request(msg) return msg['header']['msg_id'] def shutdown(self, restart=False): """Request an immediate kernel shutdown. Upon receipt of the (empty) reply, client code can safely assume that the kernel has shut down and it's safe to forcefully terminate it if it's still alive. The kernel will send the reply via a function registered with Python's atexit module, ensuring it's truly done as the kernel is done with all normal operation. """ # Send quit message to kernel. Once we implement kernel-side setattr, # this should probably be done that way, but for now this will do. msg = self.session.msg('shutdown_request', {'restart':restart}) self._queue_request(msg) return msg['header']['msg_id'] def _handle_events(self, socket, events): if events & POLLERR: self._handle_err() if events & POLLOUT: self._handle_send() if events & POLLIN: self._handle_recv() def _handle_recv(self): ident,msg = self.session.recv(self.socket, 0) self.call_handlers(msg) def _handle_send(self): try: msg = self.command_queue.get(False) except Empty: pass else: self.session.send(self.socket,msg) if self.command_queue.empty(): self.drop_io_state(POLLOUT) def _handle_err(self): # We don't want to let this go silently, so eventually we should log. raise zmq.ZMQError() def _queue_request(self, msg): self.command_queue.put(msg) self.add_io_state(POLLOUT) class SubSocketChannel(ZMQSocketChannel): """The SUB channel which listens for messages that the kernel publishes. """ def __init__(self, context, session, address): super(SubSocketChannel, self).__init__(context, session, address) self.ioloop = ioloop.IOLoop() def run(self): """The thread's main activity. Call start() instead.""" self.socket = self.context.socket(zmq.SUB) self.socket.setsockopt(zmq.SUBSCRIBE,b'') self.socket.setsockopt(zmq.IDENTITY, self.session.bsession) self.socket.connect('tcp://%s:%i' % self.address) self.iostate = POLLIN|POLLERR self.ioloop.add_handler(self.socket, self._handle_events, self.iostate) self._run_loop() def stop(self): self.ioloop.stop() super(SubSocketChannel, self).stop() def call_handlers(self, msg): """This method is called in the ioloop thread when a message arrives. Subclasses should override this method to handle incoming messages. It is important to remember that this method is called in the thread so that some logic must be done to ensure that the application leve handlers are called in the application thread. """ raise NotImplementedError('call_handlers must be defined in a subclass.') def flush(self, timeout=1.0): """Immediately processes all pending messages on the SUB channel. Callers should use this method to ensure that :method:`call_handlers` has been called for all messages that have been received on the 0MQ SUB socket of this channel. This method is thread safe. Parameters ---------- timeout : float, optional The maximum amount of time to spend flushing, in seconds. The default is one second. """ # We do the IOLoop callback process twice to ensure that the IOLoop # gets to perform at least one full poll. stop_time = time.time() + timeout for i in xrange(2): self._flushed = False self.ioloop.add_callback(self._flush) while not self._flushed and time.time() < stop_time: time.sleep(0.01) def _handle_events(self, socket, events): # Turn on and off POLLOUT depending on if we have made a request if events & POLLERR: self._handle_err() if events & POLLIN: self._handle_recv() def _handle_err(self): # We don't want to let this go silently, so eventually we should log. raise zmq.ZMQError() def _handle_recv(self): # Get all of the messages we can while True: try: ident,msg = self.session.recv(self.socket) except zmq.ZMQError: # Check the errno? # Will this trigger POLLERR? break else: if msg is None: break self.call_handlers(msg) def _flush(self): """Callback for :method:`self.flush`.""" self._flushed = True class StdInSocketChannel(ZMQSocketChannel): """A reply channel to handle raw_input requests that the kernel makes.""" msg_queue = None def __init__(self, context, session, address): super(StdInSocketChannel, self).__init__(context, session, address) self.ioloop = ioloop.IOLoop() self.msg_queue = Queue() def run(self): """The thread's main activity. Call start() instead.""" self.socket = self.context.socket(zmq.DEALER) self.socket.setsockopt(zmq.IDENTITY, self.session.bsession) self.socket.connect('tcp://%s:%i' % self.address) self.iostate = POLLERR|POLLIN self.ioloop.add_handler(self.socket, self._handle_events, self.iostate) self._run_loop() def stop(self): self.ioloop.stop() super(StdInSocketChannel, self).stop() def call_handlers(self, msg): """This method is called in the ioloop thread when a message arrives. Subclasses should override this method to handle incoming messages. It is important to remember that this method is called in the thread so that some logic must be done to ensure that the application leve handlers are called in the application thread. """ raise NotImplementedError('call_handlers must be defined in a subclass.') def input(self, string): """Send a string of raw input to the kernel.""" content = dict(value=string) msg = self.session.msg('input_reply', content) self._queue_reply(msg) def _handle_events(self, socket, events): if events & POLLERR: self._handle_err() if events & POLLOUT: self._handle_send() if events & POLLIN: self._handle_recv() def _handle_recv(self): ident,msg = self.session.recv(self.socket, 0) self.call_handlers(msg) def _handle_send(self): try: msg = self.msg_queue.get(False) except Empty: pass else: self.session.send(self.socket,msg) if self.msg_queue.empty(): self.drop_io_state(POLLOUT) def _handle_err(self): # We don't want to let this go silently, so eventually we should log. raise zmq.ZMQError() def _queue_reply(self, msg): self.msg_queue.put(msg) self.add_io_state(POLLOUT) class HBSocketChannel(ZMQSocketChannel): """The heartbeat channel which monitors the kernel heartbeat. Note that the heartbeat channel is paused by default. As long as you start this channel, the kernel manager will ensure that it is paused and un-paused as appropriate. """ time_to_dead = 3.0 socket = None poller = None _running = None _pause = None def __init__(self, context, session, address): super(HBSocketChannel, self).__init__(context, session, address) self._running = False self._pause = True def _create_socket(self): self.socket = self.context.socket(zmq.REQ) self.socket.setsockopt(zmq.IDENTITY, self.session.bsession) self.socket.connect('tcp://%s:%i' % self.address) self.poller = zmq.Poller() self.poller.register(self.socket, zmq.POLLIN) def run(self): """The thread's main activity. Call start() instead.""" self._create_socket() self._running = True while self._running: if self._pause: time.sleep(self.time_to_dead) else: since_last_heartbeat = 0.0 request_time = time.time() try: #io.rprint('Ping from HB channel') # dbg self.socket.send(b'ping') except zmq.ZMQError, e: #io.rprint('*** HB Error:', e) # dbg if e.errno == zmq.EFSM: #io.rprint('sleep...', self.time_to_dead) # dbg time.sleep(self.time_to_dead) self._create_socket() else: raise else: while True: try: self.socket.recv(zmq.NOBLOCK) except zmq.ZMQError, e: #io.rprint('*** HB Error 2:', e) # dbg if e.errno == zmq.EAGAIN: before_poll = time.time() until_dead = self.time_to_dead - (before_poll - request_time) # When the return value of poll() is an empty # list, that is when things have gone wrong # (zeromq bug). As long as it is not an empty # list, poll is working correctly even if it # returns quickly. Note: poll timeout is in # milliseconds. if until_dead > 0.0: while True: try: self.poller.poll(1000 * until_dead) except zmq.ZMQError as e: if e.errno == errno.EINTR: continue else: raise else: break since_last_heartbeat = time.time()-request_time if since_last_heartbeat > self.time_to_dead: self.call_handlers(since_last_heartbeat) break else: # FIXME: We should probably log this instead. raise else: until_dead = self.time_to_dead - (time.time() - request_time) if until_dead > 0.0: #io.rprint('sleep...', self.time_to_dead) # dbg time.sleep(until_dead) break def pause(self): """Pause the heartbeat.""" self._pause = True def unpause(self): """Unpause the heartbeat.""" self._pause = False def is_beating(self): """Is the heartbeat running and not paused.""" if self.is_alive() and not self._pause: return True else: return False def stop(self): self._running = False super(HBSocketChannel, self).stop() def call_handlers(self, since_last_heartbeat): """This method is called in the ioloop thread when a message arrives. Subclasses should override this method to handle incoming messages. It is important to remember that this method is called in the thread so that some logic must be done to ensure that the application leve handlers are called in the application thread. """ raise NotImplementedError('call_handlers must be defined in a subclass.') #----------------------------------------------------------------------------- # Main kernel manager class #----------------------------------------------------------------------------- class KernelManager(HasTraits): """ Manages a kernel for a frontend. The SUB channel is for the frontend to receive messages published by the kernel. The REQ channel is for the frontend to make requests of the kernel. The REP channel is for the kernel to request stdin (raw_input) from the frontend. """ # config object for passing to child configurables config = Instance(Config) # The PyZMQ Context to use for communication with the kernel. context = Instance(zmq.Context) def _context_default(self): return zmq.Context.instance() # The Session to use for communication with the kernel. session = Instance(Session) # The kernel process with which the KernelManager is communicating. kernel = Instance(Popen) # The addresses for the communication channels. connection_file = Unicode('') ip = Unicode(LOCALHOST) def _ip_changed(self, name, old, new): if new == '*': self.ip = '0.0.0.0' shell_port = Int(0) iopub_port = Int(0) stdin_port = Int(0) hb_port = Int(0) # The classes to use for the various channels. shell_channel_class = Type(ShellSocketChannel) sub_channel_class = Type(SubSocketChannel) stdin_channel_class = Type(StdInSocketChannel) hb_channel_class = Type(HBSocketChannel) # Protected traits. _launch_args = Any _shell_channel = Any _sub_channel = Any _stdin_channel = Any _hb_channel = Any _connection_file_written=Bool(False) def __init__(self, **kwargs): super(KernelManager, self).__init__(**kwargs) if self.session is None: self.session = Session(config=self.config) def __del__(self): if self._connection_file_written: # cleanup connection files on full shutdown of kernel we started self._connection_file_written = False try: os.remove(self.connection_file) except IOError: pass #-------------------------------------------------------------------------- # Channel management methods: #-------------------------------------------------------------------------- def start_channels(self, shell=True, sub=True, stdin=True, hb=True): """Starts the channels for this kernel. This will create the channels if they do not exist and then start them. If port numbers of 0 are being used (random ports) then you must first call :method:`start_kernel`. If the channels have been stopped and you call this, :class:`RuntimeError` will be raised. """ if shell: self.shell_channel.start() if sub: self.sub_channel.start() if stdin: self.stdin_channel.start() self.shell_channel.allow_stdin = True else: self.shell_channel.allow_stdin = False if hb: self.hb_channel.start() def stop_channels(self): """Stops all the running channels for this kernel. """ if self.shell_channel.is_alive(): self.shell_channel.stop() if self.sub_channel.is_alive(): self.sub_channel.stop() if self.stdin_channel.is_alive(): self.stdin_channel.stop() if self.hb_channel.is_alive(): self.hb_channel.stop() @property def channels_running(self): """Are any of the channels created and running?""" return (self.shell_channel.is_alive() or self.sub_channel.is_alive() or self.stdin_channel.is_alive() or self.hb_channel.is_alive()) #-------------------------------------------------------------------------- # Kernel process management methods: #-------------------------------------------------------------------------- def load_connection_file(self): """load connection info from JSON dict in self.connection_file""" with open(self.connection_file) as f: cfg = json.loads(f.read()) self.ip = cfg['ip'] self.shell_port = cfg['shell_port'] self.stdin_port = cfg['stdin_port'] self.iopub_port = cfg['iopub_port'] self.hb_port = cfg['hb_port'] self.session.key = str_to_bytes(cfg['key']) def write_connection_file(self): """write connection info to JSON dict in self.connection_file""" if self._connection_file_written: return self.connection_file,cfg = write_connection_file(self.connection_file, ip=self.ip, key=self.session.key, stdin_port=self.stdin_port, iopub_port=self.iopub_port, shell_port=self.shell_port, hb_port=self.hb_port) # write_connection_file also sets default ports: self.shell_port = cfg['shell_port'] self.stdin_port = cfg['stdin_port'] self.iopub_port = cfg['iopub_port'] self.hb_port = cfg['hb_port'] self._connection_file_written = True def start_kernel(self, **kw): """Starts a kernel process and configures the manager to use it. If random ports (port=0) are being used, this method must be called before the channels are created. Parameters: ----------- ipython : bool, optional (default True) Whether to use an IPython kernel instead of a plain Python kernel. launcher : callable, optional (default None) A custom function for launching the kernel process (generally a wrapper around ``entry_point.base_launch_kernel``). In most cases, it should not be necessary to use this parameter. **kw : optional See respective options for IPython and Python kernels. """ if self.ip not in LOCAL_IPS: raise RuntimeError("Can only launch a kernel on a local interface. " "Make sure that the '*_address' attributes are " "configured properly. " "Currently valid addresses are: %s"%LOCAL_IPS ) # write connection file / get default ports self.write_connection_file() self._launch_args = kw.copy() launch_kernel = kw.pop('launcher', None) if launch_kernel is None: if kw.pop('ipython', True): from ipkernel import launch_kernel else: from pykernel import launch_kernel self.kernel = launch_kernel(fname=self.connection_file, **kw) def shutdown_kernel(self, restart=False): """ Attempts to the stop the kernel process cleanly. If the kernel cannot be stopped, it is killed, if possible. """ # FIXME: Shutdown does not work on Windows due to ZMQ errors! if sys.platform == 'win32': self.kill_kernel() return # Pause the heart beat channel if it exists. if self._hb_channel is not None: self._hb_channel.pause() # Don't send any additional kernel kill messages immediately, to give # the kernel a chance to properly execute shutdown actions. Wait for at # most 1s, checking every 0.1s. self.shell_channel.shutdown(restart=restart) for i in range(10): if self.is_alive: time.sleep(0.1) else: break else: # OK, we've waited long enough. if self.has_kernel: self.kill_kernel() if not restart and self._connection_file_written: # cleanup connection files on full shutdown of kernel we started self._connection_file_written = False try: os.remove(self.connection_file) except IOError: pass def restart_kernel(self, now=False, **kw): """Restarts a kernel with the arguments that were used to launch it. If the old kernel was launched with random ports, the same ports will be used for the new kernel. Parameters ---------- now : bool, optional If True, the kernel is forcefully restarted *immediately*, without having a chance to do any cleanup action. Otherwise the kernel is given 1s to clean up before a forceful restart is issued. In all cases the kernel is restarted, the only difference is whether it is given a chance to perform a clean shutdown or not. **kw : optional Any options specified here will replace those used to launch the kernel. """ if self._launch_args is None: raise RuntimeError("Cannot restart the kernel. " "No previous call to 'start_kernel'.") else: # Stop currently running kernel. if self.has_kernel: if now: self.kill_kernel() else: self.shutdown_kernel(restart=True) # Start new kernel. self._launch_args.update(kw) self.start_kernel(**self._launch_args) # FIXME: Messages get dropped in Windows due to probable ZMQ bug # unless there is some delay here. if sys.platform == 'win32': time.sleep(0.2) @property def has_kernel(self): """Returns whether a kernel process has been specified for the kernel manager. """ return self.kernel is not None def kill_kernel(self): """ Kill the running kernel. """ if self.has_kernel: # Pause the heart beat channel if it exists. if self._hb_channel is not None: self._hb_channel.pause() # Attempt to kill the kernel. try: self.kernel.kill() except OSError, e: # In Windows, we will get an Access Denied error if the process # has already terminated. Ignore it. if sys.platform == 'win32': if e.winerror != 5: raise # On Unix, we may get an ESRCH error if the process has already # terminated. Ignore it. else: from errno import ESRCH if e.errno != ESRCH: raise self.kernel = None else: raise RuntimeError("Cannot kill kernel. No kernel is running!") def interrupt_kernel(self): """ Interrupts the kernel. Unlike ``signal_kernel``, this operation is well supported on all platforms. """ if self.has_kernel: if sys.platform == 'win32': from parentpoller import ParentPollerWindows as Poller Poller.send_interrupt(self.kernel.win32_interrupt_event) else: self.kernel.send_signal(signal.SIGINT) else: raise RuntimeError("Cannot interrupt kernel. No kernel is running!") def signal_kernel(self, signum): """ Sends a signal to the kernel. Note that since only SIGTERM is supported on Windows, this function is only useful on Unix systems. """ if self.has_kernel: self.kernel.send_signal(signum) else: raise RuntimeError("Cannot signal kernel. No kernel is running!") @property def is_alive(self): """Is the kernel process still running?""" # FIXME: not using a heartbeat means this method is broken for any # remote kernel, it's only capable of handling local kernels. if self.has_kernel: if self.kernel.poll() is None: return True else: return False else: # We didn't start the kernel with this KernelManager so we don't # know if it is running. We should use a heartbeat for this case. return True #-------------------------------------------------------------------------- # Channels used for communication with the kernel: #-------------------------------------------------------------------------- @property def shell_channel(self): """Get the REQ socket channel object to make requests of the kernel.""" if self._shell_channel is None: self._shell_channel = self.shell_channel_class(self.context, self.session, (self.ip, self.shell_port)) return self._shell_channel @property def sub_channel(self): """Get the SUB socket channel object.""" if self._sub_channel is None: self._sub_channel = self.sub_channel_class(self.context, self.session, (self.ip, self.iopub_port)) return self._sub_channel @property def stdin_channel(self): """Get the REP socket channel object to handle stdin (raw_input).""" if self._stdin_channel is None: self._stdin_channel = self.stdin_channel_class(self.context, self.session, (self.ip, self.stdin_port)) return self._stdin_channel @property def hb_channel(self): """Get the heartbeat socket channel object to check that the kernel is alive.""" if self._hb_channel is None: self._hb_channel = self.hb_channel_class(self.context, self.session, (self.ip, self.hb_port)) return self._hb_channel