Notebook 7: kernel usage is missing

[jtpio]

Description

With Notebook 7 the side panel shows "Kernel usage is missing".

Reproduce

1. Open a new Notebook with Notebook 7
2. Open the kernel usage side panel

Expected behavior

It should show kernel metrics like in JupyterLab:

Context

• Notebook 7.0.0
• jupyter-resource-usage main branch

[jtpio]

cc @mahendrapaipuri if you are interested in taking a look maybe.

Looks like this is the last remaining issue before being able to make a 1.0.0 release that would be compatible with JupyterLab 4 and Notebook 7.

[mahendrapaipuri]

Yes, I will have a look at it! Cheers!

[jtpio]

Thanks!

[mahendrapaipuri]

@jtpio I tried to look into it a bit yesterday but I am afraid that I am bit out of my depth here.

In the case of notebook interface, seems like the subscription here is not behaving as it should. The tracker is emitting the active kernel and connection to the slot notebookChangeCallback returns true as well. But, the callback notebookChangeCallback never gets executed. So, all the react hooks stay in undefined state.

Do you know where should I look into?

[jtpio]

Thanks for looking into it 👍

This is strange, normally it should indeed react to the currentChanged signal of the notebook tracker (used in the Notebook 7 code base). Maybe it's an issue with the lifecycle of the component (registering the callbacks too late maybe).

[jtpio]

I think #206 should fix it.