IPykernel v7 breaks this package: IndexError in the stack

[jeertmans]

Hi! When trying to upgrade my project dependencies, I noticed the following error when displaying content using VisPY (and jupyter_rfb) inside Jupyter notebooks:

Traceback (most recent call last):
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/jupyter_rfb/widget.py", line 265, in _rfb_maybe_draw
    array = self.get_frame()
            ^^^^^^^^^^^^^^^^
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/vispy/app/backends/_jupyter_rfb.py", line 191, in get_frame
    self._vispy_canvas.context.flush_commands()
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/vispy/gloo/context.py", line 172, in flush_commands
    self.glir.flush(self.shared.parser)
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/vispy/gloo/glir.py", line 584, in flush
    self._shared.flush(parser)
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/vispy/gloo/glir.py", line 506, in flush
    parser.parse(self._filter(self.clear(), parser))
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/vispy/gloo/glir.py", line 824, in parse
    self._parse(command)
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/vispy/gloo/glir.py", line 800, in _parse
    ob.set_framebuffer(*args)
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/vispy/gloo/glir.py", line 1760, in set_framebuffer
    self.deactivate()
  File "/export/home/eertmans/repositories/DiffeRT/DiffeRT/.venv/lib/python3.11/site-packages/vispy/gloo/glir.py", line 1774, in deactivate
    gl.glBindFramebuffer(gl.GL_FRAMEBUFFER, stack[-1])
                                            ~~~~~^^^^
IndexError: list index out of range

The error is raised as soon as we try to interact with the viewer (that only shows a black image).

After digging a bit, I could identify that the bug was caused when upgrading IPykernel to v7.0.0 (or above).

I looked at their changelog, and I am not sure what would cause this bug.

Any idea how to fix this?

[ianthomas23]

I think ipython/ipykernel#1438 (comment) is relevant here. It would be useful to know if the problem goes away if you disable use of kernel comms over subshells (shown in that comment)

[jeertmans]

I disabled the aforementioned setting and I did not fix (after both I restarted the kernel and also jupyter notebook server).

[jeertmans]

MWE (probably a bit long, needs uv):

git clone https://github.com/jeertmans/DiffeRT.git
git checkout 8f4b172be7fd6280f1a0f120658368046e0a3cd4

Change ipykernel<7 to ipykernel>=7 in differt/pyproject.toml.

If you don't have Rust installed, you can follow the building without Rust installation guidelines.

uv run jupyter notebook

Finally, open and run docs/source/notebooks/ray_tracing_at_city_scale.ipynb.

[almarklein]

I ran the hello world notebook (from this repo) using ipykernel 7.1.0, and it runs fine. Could you try that minimal example, so we can narrow down on the problem?

[jeertmans]

I ran the hello world notebook (from this repo) using ipykernel 7.1.0, and it runs fine. Could you try that minimal example, so we can narrow down on the problem?

Are you asking me or @ianthomas23?

[almarklein]

Are you asking me or @ianthomas23?

I meant you. Trying it on a minimal example usually helps narrow things down :)

[jeertmans]

Hi @almarklein, sorry for the delay! I tried running your hello world notebook with ipykernel>=7 and it worked just fine. The second viewer seems to take slightly more time (when compared to ipykernel<7) before it gets drawn, but I don't know if that's a bug or not.

I executed docs/source/notebooks/ray_tracing_at_city_scale.ipynb with the same Python environment, and it failed (as reported above).

[almarklein]

This should be fixed in the latest version (jupyter_rfb is now based on anywidget).

[jeertmans]

Hi @almarklein, I am still having the same issue after upgrading to the latest version: am I doing something wrong?