Errors after upgrading to 0.3.0

[palewire]

Some users following a pattern similar to the one described in #48 are getting new errors after upgrading to 0.3. When they downgrade to 0.2, the errors are gone. Here's a sample traceback.

Traceback (most recent call last):
  File "update.py", line 154, in <module>
    cli()
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "update.py", line 85, in process
    _execute_notebook(
  File "update.py", line 29, in _execute_notebook
    client.execute()
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/nbclient/util.py", line 37, in wrapped
    result = loop.run_until_complete(coro(self, *args, **kwargs))
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/base_events.py", line 612, in run_until_complete
    return future.result()
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/nbclient/client.py", line 471, in async_execute
    async with self.async_setup_kernel(**kwargs):
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/async_generator/_util.py", line 34, in __aenter__
    return await self._agen.asend(None)
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/nbclient/client.py", line 440, in async_setup_kernel
    await self.async_start_new_kernel_client(**kwargs)
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/nbclient/client.py", line 393, in async_start_new_kernel_client
    await ensure_async(self.kc.start_channels())
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/jupyter_client/client.py", line 116, in start_channels
    self.hb_channel.start()
  File "/Users/apesce/.local/share/virtualenvs/coronavirus-tracker-dljAgG8F/lib/python3.8/site-packages/jupyter_client/asynchronous/client.py", line 97, in hb_channel
    loop = asyncio.new_event_loop()
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/events.py", line 758, in new_event_loop
    return get_event_loop_policy().new_event_loop()
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/events.py", line 656, in new_event_loop
    return self._loop_factory()
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/unix_events.py", line 54, in __init__
    super().__init__(selector)
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/selector_events.py", line 61, in __init__
    self._make_self_pipe()
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/selector_events.py", line 108, in _make_self_pipe
    self._ssock, self._csock = socket.socketpair()
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/socket.py", line 571, in socketpair
    a, b = _socket.socketpair(family, type, proto)
OSError: [Errno 24] Too many open files
Exception ignored in: <function BaseEventLoop.__del__ at 0x1065fec10>
Traceback (most recent call last):
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/base_events.py", line 652, in __del__
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/unix_events.py", line 58, in close
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/selector_events.py", line 92, in close
  File "/usr/local/Cellar/python@3.8/3.8.1/Frameworks/Python.framework/Versions/3.8/lib/python3.8/asyncio/selector_events.py", line 99, in _close_self_pipe
AttributeError: '_UnixSelectorEventLoop' object has no attribute '_ssock'
make[1]: *** [process] Error 1
make: *** [update] Error 2
(coronavirus-tracker) apesce@anthonys-mbp coronavirus-tracker % [IPKernelApp] WARNING | Parent appears to have exited, shutting down.
[IPKernelApp] WARNING | Parent appears to have exited, shutting down.
[IPKernelApp] WARNING | Parent appears to have exited, shutting down.
[IPKernelApp] WARNING | Parent appears to have exited, shutting down.
[IPKernelApp] WARNING | Parent appears to have exited, shutting down.
[IPKernelApp] WARNING | Parent appears to have exited, shutting down.
[IPKernelApp] WARNING | Parent appears to have exited, shutting down.

[choldgraf]

Hmm I wonder if this is related to some of the async stuff that @davidbrochart had worked on in the last few PRs?

[choldgraf]

@palewire could you provide an example of a notebook or code snippet that reliably creates the problem?

[palewire]

I am unable to replicate the bug, which we've only seen so far on Macbooks running Python 3.8 installed via Homebrew. I'm a neckbeard who uses Ubuntu 16.04, and I'm not seeing any bugs.

Here's basically what's happening in the code. We have this function to run notebooks via nbclient:

def _execute_notebook(name, path):
    """
    Private method to execute the provided notebook and handle errors.
    """
    input_path = f"{name}.ipynb"
    output_path = f"{name}-output.ipynb"
    with open(input_path) as f:
        nb = nbformat.read(f, as_version=4)
    client = NotebookClient(
        nb,
        timeout=600,
        kernel_name='python3',
        allow_errors=False,
        force_raise_errors=True,
        resources={'metadata': {'path': path}}
    )
    try:
        client.execute()
    except CellExecutionError:
        out = None
        msg = f'Error executing the notebook "{input_path}".\n\n'
        msg += f'See notebook "{input_path}" for the traceback.'
        print(msg)
        raise
    finally:
        with open(output_path, mode='w', encoding='utf-8') as f:
            nbformat.write(nb, f)

Then we feed notebook paths into the function from a list. It's something like this:

def run():
    print("Running notebooks")
    notebook_list = [
       "notebook-1",
       "notebook-2",
       "notebook-3",
       "notebook-4",
    ]
    for notebook in notebook_list:
        notebook_filename = f'./_notebooks/{notebook}'
        print(f"- {notebook_filename}.ipynb")
        _execute_notebook(
            notebook_filename,
            path='_notebooks/'
        )

[MSeal]

Hmm I'm unlikely to be able to help because I have an older ubuntu 18 and a new ubuntu 20 machine as well. Though maybe setting the ulimit lower and running might reproduce since OSX has a lot lower default limit. I can give it a try later in the week if someone else hasn't narrowed it down. Is the error being seen consistent or sporadic? Is it after a few notebooks have run or on the first one? Might be we're not cleaning up file handles somewhere in the dependency chain.

[davidbrochart]

As @MSeal suggested, I could reproduce the bug on Ubuntu 20.04 with python3.8 by setting ulimit -n 16, although it crashed in the shell channel creation (in ZMQ) instead of the heart beat channel (in asyncio.new_event_loop). But both are caused by a new socket creation, so increasing the ulimit might solve the issue, provided that we are not leaking socket allocation.

[choldgraf]

One thing we could do is start running tests on an osx (or even windows) build on github actions. At least once we've got the bug reproducible in test form.

[davidbrochart]

Good point, sounds like a good idea in any case.

[palewire]

This error was encountered by three different users on three different Macbooks, all running the same code.

[MSeal]

I am guessing a ulimit of 256, 512, or 1024 is more accurate for a given Mac. From reading up the default and max ulimits have shifted around in this range on Mac depending on the OS version and the available RAM.

[SylvainCorlay]

This is a recurrent issue, with e.g. multiple kernels in JLab.

[MSeal]

Likely related to the comments near the end of this thread: jupyter/jupyter_client#548

[chrisjsewell]

yep got another occurence in jupyter-book/jupyter-book#867