Clicking View Traceback in the status notification (GUI) is *really* slow

[psobolewskiPhD]

🐛 Bug Report

If you get a traceback while using the GUI you get the small notification about it.
It has View Traceback button that brings up a nicely formatted traceback you can copy paste.
However, on my machine, from click to getting that window is ~1 min. with everything blocking.
This is really aweful!

💡 Steps to Reproduce

Run napari from terminal.
Trigger traceback, e.g. drag-n-drop a folder that doesn't contain images.

💡 Expected Behavior

The window should spawn within a few seconds at most.

🌎 Environment

napari: 0.4.19.post1
Platform: macOS-14.4.1-arm64-arm-64bit
System: MacOS 14.4.1
Python: 3.11.7 | packaged by conda-forge | (main, Dec 23 2023, 14:38:07) [Clang 16.0.6 ]
Qt: 5.15.8
PyQt5: 5.15.9
NumPy: 1.26.3
SciPy: 1.12.0
Dask: 2024.1.1
VisPy: 0.14.1
magicgui: 0.8.1
superqt: 0.6.1
in-n-out: 0.1.9
app-model: 0.2.4
npe2: 0.7.4

OpenGL:

• GL version: 2.1 Metal - 88
• MAX_TEXTURE_SIZE: 16384

Screens:

• screen 1: resolution 2056x1329, scale 2.0
• screen 2: resolution 2560x1440, scale 1.0

Settings path:

• /Users/sobolp/Library/Application Support/napari/napari-419_9f9c3b1d4cb071ffa9c3954dc49db19675ab479f/settings.yaml

💡 Additional Context

No response

[dalthviz]

Hi there, just in case, I gave the related logic a check and I think the performance problem comes from the highlight data being computed for the full traceback multiple times (once per content block/paragraph) here:

napari/napari/_qt/code_syntax_highlight.py

Lines 75 to 80 in 7fc49c1

	def highlightBlock(self, text):
	cb = self.currentBlock()
	p = cb.position()
	text = self.document().toPlainText() + '\n'
	highlight(text, self.lexer, self.formatter)

Changing the logic to do the highlight computation only once seems like helps. So changing things to look something like a6df139

A preview:

Happy to open a PR if that makes sense :)

[psobolewskiPhD]

I think that makes sense, @Czaki any thoughts? you wrote it 😉
Also, this looks to have been up-streamed to superqt:
https://github.com/pyapp-kit/superqt/blob/0ec5cd3a2f967f04f0240e2421a6fd2f2f7fcf25/src/superqt/utils/_code_syntax_highlight.py

Maybe we should fix there and then use superqt version in napari?

[Czaki]

Maybe we should fix there and then use superqt version in napari?

I think that this will be best solution.