Cannot run qtconsole with existing kernel in jupyter-client 7

[ghost]

Issue description

Unable to run qtconsole with existing kernel

Steps to reproduce

1. launch a kernel

$ jupyter notebook

select a new Python 3 notebook

2. run qtconsole, connecting to existing kernel

$ jupyter qtconsole --existing

The QtConsole window appears and is blank. The error output is shown below.

ERROR:tornado.general:Uncaught exception in ZMQStream callback
Traceback (most recent call last):
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
    callback(*args, **kwargs)
  File "/home/user/.local/lib/python3.9/site-packages/jupyter_client/threaded.py", line 121, in _handle_recv
    msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
  File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
    self._check_running()
  File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
    raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:tornado.general:Uncaught exception in zmqstream callback
Traceback (most recent call last):
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 452, in _handle_events
    self._handle_recv()
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 481, in _handle_recv
    self._run_callback(callback, msg)
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
    callback(*args, **kwargs)
  File "/home/user/.local/lib/python3.9/site-packages/jupyter_client/threaded.py", line 121, in _handle_recv
    msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
  File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
    self._check_running()
  File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
    raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:asyncio:Exception in callback BaseAsyncIOLoop._handle_events(20, 1)
handle: <Handle BaseAsyncIOLoop._handle_events(20, 1)>
Traceback (most recent call last):
  File "/usr/lib/python3.9/asyncio/events.py", line 80, in _run
    self._context.run(self._callback, *self._args)
  File "/home/user/.local/lib/python3.9/site-packages/tornado/platform/asyncio.py", line 189, in _handle_events
    handler_func(fileobj, events)
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 452, in _handle_events
    self._handle_recv()
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 481, in _handle_recv
    self._run_callback(callback, msg)
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
    callback(*args, **kwargs)
  File "/home/user/.local/lib/python3.9/site-packages/jupyter_client/threaded.py", line 121, in _handle_recv
    msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
  File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
    self._check_running()
  File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
    raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:tornado.general:Uncaught exception in ZMQStream callback
Traceback (most recent call last):
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
    callback(*args, **kwargs)
  File "/home/user/.local/lib/python3.9/site-packages/jupyter_client/threaded.py", line 121, in _handle_recv
    msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
  File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
    self._check_running()
  File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
    raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:tornado.general:Uncaught exception in zmqstream callback
Traceback (most recent call last):
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 452, in _handle_events
    self._handle_recv()
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 481, in _handle_recv
    self._run_callback(callback, msg)
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
    callback(*args, **kwargs)
  File "/home/user/.local/lib/python3.9/site-packages/jupyter_client/threaded.py", line 121, in _handle_recv
    msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
  File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
    self._check_running()
  File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
    raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:asyncio:Exception in callback BaseAsyncIOLoop._handle_events(18, 1)
handle: <Handle BaseAsyncIOLoop._handle_events(18, 1)>
Traceback (most recent call last):
  File "/usr/lib/python3.9/asyncio/events.py", line 80, in _run
    self._context.run(self._callback, *self._args)
  File "/home/user/.local/lib/python3.9/site-packages/tornado/platform/asyncio.py", line 189, in _handle_events
    handler_func(fileobj, events)
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 452, in _handle_events
    self._handle_recv()
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 481, in _handle_recv
    self._run_callback(callback, msg)
  File "/home/user/.local/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
    callback(*args, **kwargs)
  File "/home/user/.local/lib/python3.9/site-packages/jupyter_client/threaded.py", line 121, in _handle_recv
    msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
  File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
    self._check_running()
  File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
    raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
/usr/lib/python3.9/site-packages/pkg_resources/_vendor/packaging/utils.py:8: RuntimeWarning: coroutine 'get_msg' was never awaited
  from .tags import Tag, parse_tag
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
/usr/lib/python3.9/site-packages/pkg_resources/_vendor/pyparsing.py:3270: RuntimeWarning: coroutine 'get_msg' was never awaited
  if all(isinstance(expr, basestring) for expr in exprs):
RuntimeWarning: Enable tracemalloc to get the object allocation traceback

Environment

_$ pip list --user | grep jupyter
jupyter              1.0.0
jupyter-client       7.1.1
jupyter-console      6.4.0
jupyter-core         4.9.1
jupyterlab-pygments  0.1.2
jupyterlab-widgets   1.0.2
_$ pip list --user | grep ipy
ipykernel            6.7.0
ipython              8.0.0
ipython-genutils     0.2.0
ipywidgets           7.6.5
_$ pip list --user | grep zmq
pyzmq                22.3.0
_$ python --version
Python 3.9.9
_$ cat ~/.jupyter/jupyter_qtconsole_config.py
c = get_config()

c.ConsoleWidget.scrollbar_visibility = False

c.ConsoleWidget.font_family = "Inconsolata"
c.ConsoleWidget.font_size = 14

c.JupyterQtConsoleApp.hide_menubar = True

c.JupyterWidget.include_other_output = True

[ghost]

I repeated the above with the current main branch of python_console, qtconsole, and jupyter_client, and got the same issue with a similar error message (below)

Error

ERROR:tornado.general:Uncaught exception in ZMQStream callback
Traceback (most recent call last):
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
   callback(*args, **kwargs)
 File "/home/user/jupyter-test/jupyter_client/jupyter_client/threaded.py", line 121, in _handle_recv
   msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
 File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
   self._check_running()
 File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
   raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:tornado.general:Uncaught exception in zmqstream callback
Traceback (most recent call last):
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 452, in _handle_events
   self._handle_recv()
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 481, in _handle_recv
   self._run_callback(callback, msg)
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
   callback(*args, **kwargs)
 File "/home/user/jupyter-test/jupyter_client/jupyter_client/threaded.py", line 121, in _handle_recv
   msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
 File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
   self._check_running()
 File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
   raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:asyncio:Exception in callback BaseAsyncIOLoop._handle_events(20, 1)
handle: <Handle BaseAsyncIOLoop._handle_events(20, 1)>
Traceback (most recent call last):
 File "/usr/lib/python3.9/asyncio/events.py", line 80, in _run
   self._context.run(self._callback, *self._args)
 File "/home/user/jupyter-test/lib/python3.9/site-packages/tornado/platform/asyncio.py", line 189, in _handle_events
   handler_func(fileobj, events)
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 452, in _handle_events
   self._handle_recv()
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 481, in _handle_recv
   self._run_callback(callback, msg)
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
   callback(*args, **kwargs)
 File "/home/user/jupyter-test/jupyter_client/jupyter_client/threaded.py", line 121, in _handle_recv
   msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
 File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
   self._check_running()
 File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
   raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:tornado.general:Uncaught exception in ZMQStream callback
Traceback (most recent call last):
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
   callback(*args, **kwargs)
 File "/home/user/jupyter-test/jupyter_client/jupyter_client/threaded.py", line 121, in _handle_recv
   msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
 File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
   self._check_running()
 File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
   raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:tornado.general:Uncaught exception in zmqstream callback
Traceback (most recent call last):
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 452, in _handle_events
   self._handle_recv()
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 481, in _handle_recv
   self._run_callback(callback, msg)
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
   callback(*args, **kwargs)
 File "/home/user/jupyter-test/jupyter_client/jupyter_client/threaded.py", line 121, in _handle_recv
   msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
 File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
   self._check_running()
 File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
   raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
ERROR:asyncio:Exception in callback BaseAsyncIOLoop._handle_events(18, 1)
handle: <Handle BaseAsyncIOLoop._handle_events(18, 1)>
Traceback (most recent call last):
 File "/usr/lib/python3.9/asyncio/events.py", line 80, in _run
   self._context.run(self._callback, *self._args)
 File "/home/user/jupyter-test/lib/python3.9/site-packages/tornado/platform/asyncio.py", line 189, in _handle_events
   handler_func(fileobj, events)
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 452, in _handle_events
   self._handle_recv()
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 481, in _handle_recv
   self._run_callback(callback, msg)
 File "/home/user/jupyter-test/lib/python3.9/site-packages/zmq/eventloop/zmqstream.py", line 431, in _run_callback
   callback(*args, **kwargs)
 File "/home/user/jupyter-test/jupyter_client/jupyter_client/threaded.py", line 121, in _handle_recv
   msg_list = self.ioloop._asyncio_event_loop.run_until_complete(get_msg(future_msg))
 File "/usr/lib/python3.9/asyncio/base_events.py", line 618, in run_until_complete
   self._check_running()
 File "/usr/lib/python3.9/asyncio/base_events.py", line 580, in _check_running
   raise RuntimeError(
RuntimeError: Cannot run the event loop while another loop is running
/usr/lib/python3.9/sre_parse.py:499: RuntimeWarning: coroutine 'get_msg' was never awaited
 sourceget = source.get
RuntimeWarning: Enable tracemalloc to get the object allocation traceback

[ghost]

I've confirmed that this works with jupyter-client version 6.1.12

[astromancer]

The ability to connect to an existing kernel is critical to my workflow. Hope this gets a fix soon.

[bellecp]

I am running into the same issue as well. One quick fix is to

1. launch the qtconsole (e.g., $ jupyter qtconsole &) which may open an undesired new kernel
2. file -> new tab with existing kernel. Then, pick the desired kernel file
3. close the tab of the undesired kernel opened in step 1