Share an IOLoop among Qt channels, rather than one each

IPython/kernel/blocking/channels.py

@@ -1,143 +1,143 b''
 """Blocking channels
 
 Useful for test suites and blocking terminal interfaces.
 """
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 try:
     from queue import Queue, Empty  # Py 3
 except ImportError:
     from Queue import Queue, Empty  # Py 2
 
 from IPython.kernel.channelsabc import ShellChannelABC, IOPubChannelABC, \
     StdInChannelABC
 from IPython.kernel.channels import  HBChannel,\
     make_iopub_socket, make_shell_socket, make_stdin_socket,\
     InvalidPortNumber, major_protocol_version
 from IPython.utils.py3compat import string_types, iteritems
 
 # 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, string_types):
             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 iteritems(dct):
         if not isinstance(k, string_types):
             raise ValueError('key %r in dict must be a string' % k)
         if not isinstance(v, string_types):
             raise ValueError('value %r in dict must be a string' % v)
 
 
 class ZMQSocketChannel(object):
     """The base class for the channels that use ZMQ sockets."""
     session = None
     socket = None
     stream = None
     _exiting = False
     proxy_methods = []
 
-    def __init__(self, socket, session):
+    def __init__(self, socket, session, loop=None):
         """Create a channel.
 
         Parameters
         ----------
-        context : :class:`zmq.Context`
-            The ZMQ context to use.
+        socket : :class:`zmq.Socket`
+            The ZMQ socket to use.
         session : :class:`session.Session`
             The session to use.
-        address : zmq url
-            Standard (ip, port) tuple that the kernel is listening on.
+        loop
+            Unused here, for other implementations
         """
         super(ZMQSocketChannel, self).__init__()
 
         self.socket = socket
         self.session = session
 
     def _recv(self, **kwargs):
         msg = self.socket.recv_multipart(**kwargs)
         ident,smsg = self.session.feed_identities(msg)
         return self.session.deserialize(smsg)
 
     def get_msg(self, block=True, timeout=None):
         """ Gets a message if there is one that is ready. """
         if block:
             if timeout is not None:
                 timeout *= 1000  # seconds to ms
             ready = self.socket.poll(timeout)
         else:
             ready = self.socket.poll(timeout=0)
 
         if ready:
             return self._recv()
         else:
             raise Empty
 
     def get_msgs(self):
         """ Get all messages that are currently ready. """
         msgs = []
         while True:
             try:
                 msgs.append(self.get_msg(block=False))
             except Empty:
                 break
         return msgs
 
     def msg_ready(self):
         """ Is there a message that has been received? """
         return bool(self.socket.poll(timeout=0))
 
     def close(self):
         if self.socket is not None:
             try:
                 self.socket.close(linger=0)
             except Exception:
                 pass
             self.socket = None
     stop =  close
 
     def is_alive(self):
         return (self.socket is not None)
 
     @property
     def address(self):
         """Get the channel's address as a zmq url string.
 
         These URLS have the form: 'tcp://127.0.0.1:5555'.
         """
         return self._address
 
     def _queue_send(self, msg):
         """Pass a message to the ZMQ socket to send
         """
         self.session.send(self.socket, msg)
 
     def start(self):
         pass
 
 
 
 class BlockingHBChannel(HBChannel):
 
     # This kernel needs quicker monitoring, shorten to 1 sec.
     # less than 0.5s is unreliable, and will get occasional
     # false reports of missed beats.
     time_to_dead = 1.
 
     def call_handlers(self, since_last_heartbeat):
         """ Pause beating on missed heartbeat. """
         pass

IPython/kernel/client.py

@@ -1,375 +1,377 b''
 """Base class to manage the interaction with a running kernel"""
 
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
 from __future__ import absolute_import
 from IPython.kernel.channels import validate_string_dict, major_protocol_version
 from IPython.utils.py3compat import string_types
 
 import zmq
 
 from IPython.utils.traitlets import (
     Any, Instance, Type,
 )
 
 from .channelsabc import (
     ShellChannelABC, IOPubChannelABC, HBChannelABC, StdInChannelABC
 )
 from .channels import (
     make_shell_socket, make_stdin_socket, make_iopub_socket
 )
 from .clientabc import KernelClientABC
 from .connect import ConnectionFileMixin
 
 
 class KernelClient(ConnectionFileMixin):
     """Communicates with a single kernel on any host via zmq channels.
 
     There are four channels associated with each kernel:
 
     * shell: for request/reply calls to the kernel.
     * iopub: for the kernel to publish results to frontends.
     * hb: for monitoring the kernel's heartbeat.
     * stdin: for frontends to reply to raw_input calls in the kernel.
 
     The methods of the channels are exposed as methods of the client itself
     (KernelClient.execute, complete, history, etc.).
     See the channels themselves for documentation of these methods.
 
     """
 
     # The PyZMQ Context to use for communication with the kernel.
     context = Instance(zmq.Context)
     def _context_default(self):
         return zmq.Context.instance()
 
     # The classes to use for the various channels
     shell_channel_class = Type(ShellChannelABC)
     iopub_channel_class = Type(IOPubChannelABC)
     stdin_channel_class = Type(StdInChannelABC)
     hb_channel_class = Type(HBChannelABC)
 
     # Protected traits
     _shell_channel = Any
     _iopub_channel = Any
     _stdin_channel = Any
     _hb_channel = Any
 
     # flag for whether execute requests should be allowed to call raw_input:
     allow_stdin = True
 
     #--------------------------------------------------------------------------
     # Channel proxy methods
     #--------------------------------------------------------------------------
 
     def _get_msg(channel, *args, **kwargs):
         return channel.get_msg(*args, **kwargs)
 
     def get_shell_msg(self, *args, **kwargs):
         """Get a message from the shell channel"""
         return self.shell_channel.get_msg(*args, **kwargs)
 
     def get_iopub_msg(self, *args, **kwargs):
         """Get a message from the iopub channel"""
         return self.iopub_channel.get_msg(*args, **kwargs)
 
     def get_stdin_msg(self, *args, **kwargs):
         """Get a message from the stdin channel"""
         return self.stdin_channel.get_msg(*args, **kwargs)
 
     #--------------------------------------------------------------------------
     # Channel management methods
     #--------------------------------------------------------------------------
 
     def start_channels(self, shell=True, iopub=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 (their activity runs in a thread). If port numbers of 0 are
         being used (random ports) then you must first call
         :meth:`start_kernel`. If the channels have been stopped and you
         call this, :class:`RuntimeError` will be raised.
         """
         if shell:
             self.shell_channel.start()
             self.kernel_info()
         if iopub:
             self.iopub_channel.start()
         if stdin:
             self.stdin_channel.start()
             self.allow_stdin = True
         else:
             self.allow_stdin = False
         if hb:
             self.hb_channel.start()
 
     def stop_channels(self):
         """Stops all the running channels for this kernel.
 
         This stops their event loops and joins their threads.
         """
         if self.shell_channel.is_alive():
             self.shell_channel.stop()
         if self.iopub_channel.is_alive():
             self.iopub_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.iopub_channel.is_alive() or
                 self.stdin_channel.is_alive() or self.hb_channel.is_alive())
 
+    ioloop = None  # Overridden in subclasses that use pyzmq event loop
+
     @property
     def shell_channel(self):
         """Get the shell channel object for this kernel."""
         if self._shell_channel is None:
             url = self._make_url('shell')
             self.log.debug("connecting shell channel to %s", url)
             socket = make_shell_socket(self.context, self.session.bsession, url)
             self._shell_channel = self.shell_channel_class(
-                socket, self.session
+                socket, self.session, self.ioloop
             )
         return self._shell_channel
 
     @property
     def iopub_channel(self):
         """Get the iopub channel object for this kernel."""
         if self._iopub_channel is None:
             url = self._make_url('iopub')
             self.log.debug("connecting iopub channel to %s", url)
             socket = make_iopub_socket(self.context, self.session.bsession, url)
             self._iopub_channel = self.iopub_channel_class(
-                socket, self.session
+                socket, self.session, self.ioloop
             )
         return self._iopub_channel
 
     @property
     def stdin_channel(self):
         """Get the stdin channel object for this kernel."""
         if self._stdin_channel is None:
             url = self._make_url('stdin')
             self.log.debug("connecting stdin channel to %s", url)
             socket = make_stdin_socket(self.context, self.session.bsession, url)
             self._stdin_channel = self.stdin_channel_class(
-                socket, self.session
+                socket, self.session, self.ioloop
             )
         return self._stdin_channel
 
     @property
     def hb_channel(self):
         """Get the hb channel object for this kernel."""
         if self._hb_channel is None:
             url = self._make_url('hb')
             self.log.debug("connecting heartbeat channel to %s", url)
             self._hb_channel = self.hb_channel_class(
                 self.context, self.session, url
             )
         return self._hb_channel
 
     def is_alive(self):
         """Is the kernel process still running?"""
         if self._hb_channel is not None:
             # We didn't start the kernel with this KernelManager so we
             # use the heartbeat.
             return self._hb_channel.is_beating()
         else:
             # no heartbeat and not local, we can't tell if it's running,
             # so naively return True
             return True
 
 
     # Methods to send specific messages on channels
     def execute(self, code, silent=False, store_history=True,
                 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, and
             will force store_history to be False.
 
         store_history : bool, optional (default True)
             If set, the kernel will store command history.  This is forced
             to be False if silent is True.
 
         user_expressions : dict, optional
             A dict mapping names to expressions to be evaluated in the user's
             dict. The expression values are returned as strings formatted using
             :func:`repr`.
 
         allow_stdin : bool, optional (default self.allow_stdin)
             Flag for whether the kernel can send stdin requests to frontends.
 
             Some frontends (e.g. the Notebook) do not support stdin requests.
             If raw_input is called from code executed from such a frontend, a
             StdinNotImplementedError will be raised.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         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, string_types):
             raise ValueError('code %r must be a string' % code)
         validate_string_dict(user_expressions)
 
         # Create class for content/msg creation. Related to, but possibly
         # not in Session.
         content = dict(code=code, silent=silent, store_history=store_history,
                        user_expressions=user_expressions,
                        allow_stdin=allow_stdin,
                        )
         msg = self.session.msg('execute_request', content)
         self.shell_channel._queue_send(msg)
         return msg['header']['msg_id']
 
     def complete(self, code, cursor_pos=None):
         """Tab complete text in the kernel's namespace.
 
         Parameters
         ----------
         code : str
             The context in which completion is requested.
             Can be anything between a variable name and an entire cell.
         cursor_pos : int, optional
             The position of the cursor in the block of code where the completion was requested.
             Default: ``len(code)``
 
         Returns
         -------
         The msg_id of the message sent.
         """
         if cursor_pos is None:
             cursor_pos = len(code)
         content = dict(code=code, cursor_pos=cursor_pos)
         msg = self.session.msg('complete_request', content)
         self.shell_channel._queue_send(msg)
         return msg['header']['msg_id']
 
     def inspect(self, code, cursor_pos=None, detail_level=0):
         """Get metadata information about an object in the kernel's namespace.
 
         It is up to the kernel to determine the appropriate object to inspect.
 
         Parameters
         ----------
         code : str
             The context in which info is requested.
             Can be anything between a variable name and an entire cell.
         cursor_pos : int, optional
             The position of the cursor in the block of code where the info was requested.
             Default: ``len(code)``
         detail_level : int, optional
             The level of detail for the introspection (0-2)
 
         Returns
         -------
         The msg_id of the message sent.
         """
         if cursor_pos is None:
             cursor_pos = len(code)
         content = dict(code=code, cursor_pos=cursor_pos,
             detail_level=detail_level,
         )
         msg = self.session.msg('inspect_request', content)
         self.shell_channel._queue_send(msg)
         return msg['header']['msg_id']
 
     def history(self, raw=True, output=False, hist_access_type='range', **kwargs):
         """Get entries from the kernel's 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.shell_channel._queue_send(msg)
         return msg['header']['msg_id']
 
     def kernel_info(self):
         """Request kernel info."""
         msg = self.session.msg('kernel_info_request')
         self.shell_channel._queue_send(msg)
         return msg['header']['msg_id']
 
     def _handle_kernel_info_reply(self, msg):
         """handle kernel info reply
 
         sets protocol adaptation version
         """
         adapt_version = int(msg['content']['protocol_version'].split('.')[0])
         if adapt_version != major_protocol_version:
             self.session.adapt_version = adapt_version
 
     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.shell_channel._queue_send(msg)
         return msg['header']['msg_id']
 
     def is_complete(self, code):
         msg = self.session.msg('is_complete_request', {'code': code})
         self.shell_channel._queue_send(msg)
         return msg['header']['msg_id']
 
     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.stdin_channel._queue_send(msg)
 
 
 KernelClientABC.register(KernelClient)

IPython/qt/client.py

@@ -1,257 +1,278 b''
 """ Defines a KernelClient that provides signals and slots.
 """
 import atexit
 import errno
 from threading import Thread
 import time
 
 import zmq
 # import ZMQError in top-level namespace, to avoid ugly attribute-error messages
 # during garbage collection of threads at exit:
 from zmq import ZMQError
 from zmq.eventloop import ioloop, zmqstream
 
 from IPython.external.qt import QtCore
 
 # Local imports
-from IPython.utils.traitlets import Type
+from IPython.utils.traitlets import Type, Instance
 from IPython.kernel.channels import HBChannel,\
     make_shell_socket, make_iopub_socket, make_stdin_socket
 from IPython.kernel import KernelClient
 
 from .kernel_mixins import (QtHBChannelMixin, QtKernelClientMixin)
 from .util import SuperQObject
 
 class QtHBChannel(QtHBChannelMixin, HBChannel):
     pass
 
 from IPython.core.release import kernel_protocol_version_info
 
 from IPython.kernel.channelsabc import (
     ShellChannelABC, IOPubChannelABC, StdInChannelABC,
 )
 from IPython.utils.py3compat import string_types, iteritems
 
 major_protocol_version = kernel_protocol_version_info[0]
 
 class InvalidPortNumber(Exception):
     pass
 
 # some utilities to validate message structure, these might get moved elsewhere
 # if they prove to have more generic utility
 
 
 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 iteritems(dct):
         if not isinstance(k, string_types):
             raise ValueError('key %r in dict must be a string' % k)
         if not isinstance(v, string_types):
             raise ValueError('value %r in dict must be a string' % v)
 
 
 
-class QtZMQSocketChannel(SuperQObject, Thread):
+class QtZMQSocketChannel(SuperQObject):
     """The base class for the channels that use ZMQ sockets."""
     session = None
     socket = None
     ioloop = None
     stream = None
-    _exiting = False
-    proxy_methods = []
-
-    # Emitted when the channel is started.
-    started = QtCore.Signal()
-
-    # Emitted when the channel is stopped.
-    stopped = QtCore.Signal()
 
     message_received = QtCore.Signal(object)
 
     #---------------------------------------------------------------------------
     # InProcessChannel interface
     #---------------------------------------------------------------------------
 
     def call_handlers_later(self, *args, **kwds):
         """ Call the message handlers later.
         """
         do_later = lambda: self.call_handlers(*args, **kwds)
         QtCore.QTimer.singleShot(0, do_later)
 
     def process_events(self):
         """ Process any pending GUI events.
         """
         QtCore.QCoreApplication.instance().processEvents()
 
-    def __init__(self, socket, session):
+    def __init__(self, socket, session, loop):
         """Create a channel.
 
         Parameters
         ----------
-        context : :class:`zmq.Context`
-            The ZMQ context to use.
+        socket : :class:`zmq.Socket`
+            The ZMQ socket to use.
         session : :class:`session.Session`
             The session to use.
-        address : zmq url
-            Standard (ip, port) tuple that the kernel is listening on.
+        loop
+            A pyzmq ioloop to connect the socket to using a ZMQStream
         """
         super(QtZMQSocketChannel, self).__init__()
-        self.daemon = True
 
         self.socket = socket
         self.session = session
-        atexit.register(self._notice_exit)
-        self.ioloop = ioloop.IOLoop()
+        self.ioloop = loop
 
-    def _notice_exit(self):
-        self._exiting = True
+        self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
+        self.stream.on_recv(self._handle_recv)
 
-    def _run_loop(self):
-        """Run my loop, ignoring EINTR events in the poller"""
-        while True:
-            try:
-                self.ioloop.start()
-            except ZMQError as e:
-                if e.errno == errno.EINTR:
-                    continue
-                else:
-                    raise
-            except Exception:
-                if self._exiting:
-                    break
-                else:
-                    raise
-            else:
-                break
+    _is_alive = False
+    def is_alive(self):
+        return self._is_alive
 
     def start(self):
-        """ Reimplemented to emit signal.
-        """
-        super(QtZMQSocketChannel, self).start()
-        self.started.emit()
-
-    def run(self):
-        """The thread's main activity.  Call start() instead."""
-        self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
-        self.stream.on_recv(self._handle_recv)
-        self._run_loop()
+        self._is_alive = True
 
     def stop(self):
-        """Stop the channel's event loop and join its thread.
-
-        This calls :meth:`~threading.Thread.join` and returns when the thread
-        terminates. :class:`RuntimeError` will be raised if
-        :meth:`~threading.Thread.start` is called again.
-        """
-        if self.ioloop is not None:
-            self.ioloop.stop()
-        self.join()
-        self.close()
-        self.stopped.emit()
+        self._is_alive = False
 
     def close(self):
-        if self.ioloop is not None:
-            try:
-                self.ioloop.close(all_fds=True)
-            except Exception:
-                pass
         if self.socket is not None:
             try:
                 self.socket.close(linger=0)
             except Exception:
                 pass
             self.socket = None
 
     @property
     def address(self):
         """Get the channel's address as a zmq url string.
 
         These URLS have the form: 'tcp://127.0.0.1:5555'.
         """
         return self._address
 
     def _queue_send(self, msg):
         """Queue a message to be sent from the IOLoop's thread.
 
         Parameters
         ----------
         msg : message to send
 
         This is threadsafe, as it uses IOLoop.add_callback to give the loop's
         thread control of the action.
         """
         def thread_send():
             self.session.send(self.stream, msg)
         self.ioloop.add_callback(thread_send)
 
     def _handle_recv(self, msg):
         """Callback for stream.on_recv.
 
         Unpacks message, and calls handlers with it.
         """
         ident,smsg = self.session.feed_identities(msg)
         msg = self.session.deserialize(smsg)
         self.call_handlers(msg)
 
     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 level
         handlers are called in the application thread.
         """
         # Emit the generic signal.
         self.message_received.emit(msg)
 
     def flush(self, timeout=1.0):
         """Immediately processes all pending messages on this channel.
 
         This is only used for the IOPub channel.
 
         Callers should use this method to ensure that :meth:`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 range(2):
             self._flushed = False
             self.ioloop.add_callback(self._flush)
             while not self._flushed and time.time() < stop_time:
                 time.sleep(0.01)
 
     def _flush(self):
         """Callback for :method:`self.flush`."""
         self.stream.flush()
         self._flushed = True
 
 
+class IOLoopThread(Thread):
+    """Run a pyzmq ioloop in a thread to send and receive messages
+    """
+    def __init__(self, loop):
+        super(IOLoopThread, self).__init__()
+        self.daemon = True
+        atexit.register(self._notice_exit)
+        self.ioloop = loop or ioloop.IOLoop()
+
+    def _notice_exit(self):
+        self._exiting = True
+
+    def run(self):
+        """Run my loop, ignoring EINTR events in the poller"""
+        while True:
+            try:
+                self.ioloop.start()
+            except ZMQError as e:
+                if e.errno == errno.EINTR:
+                    continue
+                else:
+                    raise
+            except Exception:
+                if self._exiting:
+                    break
+                else:
+                    raise
+            else:
+                break
+
+    def stop(self):
+        """Stop the channel's event loop and join its thread.
+
+        This calls :meth:`~threading.Thread.join` and returns when the thread
+        terminates. :class:`RuntimeError` will be raised if
+        :meth:`~threading.Thread.start` is called again.
+        """
+        if self.ioloop is not None:
+            self.ioloop.stop()
+        self.join()
+        self.close()
+
+    def close(self):
+        if self.ioloop is not None:
+            try:
+                self.ioloop.close(all_fds=True)
+            except Exception:
+                pass
+
+
 class QtKernelClient(QtKernelClientMixin, KernelClient):
     """ A KernelClient that provides signals and slots.
     """
+
+    _ioloop = None
+    @property
+    def ioloop(self):
+        if self._ioloop is None:
+            self._ioloop = ioloop.IOLoop()
+        return self._ioloop
+
+    ioloop_thread = Instance(IOLoopThread)
+
     def start_channels(self, shell=True, iopub=True, stdin=True, hb=True):
         if shell:
             self.shell_channel.message_received.connect(self._check_kernel_info_reply)
+
+        self.channel_listener_thread = IOLoopThread(self.ioloop)
+        self.channel_listener_thread.start()
+
         super(QtKernelClient, self).start_channels(shell, iopub, stdin, hb)
 
     def _check_kernel_info_reply(self, msg):
         if msg['msg_type'] == 'kernel_info_reply':
             self._handle_kernel_info_reply(msg)
             self.shell_channel.message_received.disconnect(self._check_kernel_info_reply)
 
+    def stop_channels(self):
+        super(QtKernelClient, self).stop_channels()
+        if self.ioloop_thread.is_alive():
+            self.ioloop_thread.stop()
+
     iopub_channel_class = Type(QtZMQSocketChannel)
     shell_channel_class = Type(QtZMQSocketChannel)
     stdin_channel_class = Type(QtZMQSocketChannel)
     hb_channel_class = Type(QtHBChannel)