Notification initialisation is not properly working

[ruzzle]

In Jupyter Lab (version 4.0.9), I tried to use panel notifications, like:

import panel as pn

pn.extension(notifications=True)
pn.state.notifications.error('test')

The strange thing was that on the first time, the notification did not appear, but every time afterwards, the notification did appear. I produced this issue using the official docker image (quay.io/jupyter/minimal-notebook) and installed panel (1.3.6) via pip.

I eventually found the issue by debugging cell execution twice. During the first execution of pn.extension() and the second execution I found a difference: It appeared that panel_extension._display_globals in panel.config is not called the first time but only the second time. I presume this should not be the case?

To verify, I added panel_extension._display_globals() manually after loading the extension, which resolved the issue

For completion, here is also some system context:

IPython          : 8.18.1
ipykernel        : 6.26.0
ipywidgets       : not installed
jupyter_client   : 8.6.0
jupyter_core     : 5.5.0
jupyter_server   : 2.12.1
jupyterlab       : 4.0.9
nbclient         : 0.8.0
nbconvert        : 7.12.0
nbformat         : 5.9.2
notebook         : 7.0.6
qtconsole        : not installed
traitlets        : 5.14.0

[philippjfr]

I can reproduce your issue but not what you reported about the cause, specifically _display_globals IS called the first time for me. For me it's not working because Notyf doesn't appear to be loaded correctly.

[philippjfr]

Nevermind, the Notyf thing was due a local development version. I can't reproduce your issue at all unfortunately. Do you have an idea what causes _display_globals not to be called? The only thing I can think of is that you maybe have another extension call in the same cell, e.g. this reproduces the issue for me:

import panel as pn
import hvplot.pandas # Initializes the extension once

pn.extension(notifications=True)

[ruzzle]

With the following you should be able to reproduce it:

docker run --rm -t -i -p 8888:8888 quay.io/jupyter/minimal-notebook
docker exec -t -i <container_name> pip install panel

Then open up jupyter lab, create a new notebook, paste the code and execute

[ruzzle]

To add to your question, _display_globals is called within the __call__ function only if published is set to False, so I presume published is somehow set to True the first time.

Assuming that is the case, looking at the code in __call__, it may have something to do with the assignment of published, but cannot tell what it would be...

nb_loaded = published = getattr(self, '_repeat_execution_in_cell', False)

[philippjfr]

The real issue seems to be that when the cell executes for the first time the Jupyter comm machinery does not seem to be fully set up, so while the NotificationArea component is rendered it is not correctly connected to the Comm, which means messages sent to it won't be registered. This is likely a general problem with all components rendered in the first cell. I'll keep investigating.

[philippjfr]

I've figured out the issue. On first load BokehJS and Panel.JS aren't initialized yet and these take a while to load. However on the server side we don't know this so we instantiate the Comm that will be used to send data to the frontend. However if you attempt to initialize a Comm that hasn't yet been set up on the frontend it will never connect, so we end up in a scenario where even once everything is initialized any Comm that was set up before the frontend was fully initialized will not receive messages correctly. Will have to see if there's some way around this, but it's sadly not a simple problem.