1578587 - CodeMirror 1min+ hangs on large minified files when clicking through from Console

Status: RESOLVED FIXED

(DevTools :: Debugger, defect, P2)

Description

[:Harald Kirschner :digitarald]

STR:

1. Open Console on https://www.notion.so/Station-s-public-roadmap-030f47e10b36450f91377035949b51ba?p=6b8d066194de4999acd53b2fb44108b8
2. Follow a log link to app*.js to open it in Debugger

AR: 160s hang on Quantum reference machine. MBP isn't much better.

Windows profile: https://perfht.ml/32s9Yih
Again CodeMirror</Et.prototype.column and js::str_indexOf.

ER: Open in reasonable time.

I could not get a hang when opening the file directly from the Debugger sources list, so maybe bug 1553291 helped with that

Comment 1

[Jason Laster [:jlast]]

it looks like part of this is the fact that app-*.js has 24090 scripts.

Comment 2

[David Walsh :davidwalsh]

In the case that a file is ultra-massive, like this one, should we show a warning message before trying to render its contents? Rendering message may signal to the user that the debugger may not be as responsive. Text editors have this pattern.

Comment 3

[:Harald Kirschner :digitarald]

That might be useful, but this assumes that users might want to not open the file. If an issue happens in a heavy file, the user doesn't have much of a choice, right?

But having an upper limit and having a prompt UI similar to Atom or VSCode would be still good to have to prevent freezes of more than a few sec.

Comment 4

[mattheww]

I'm not sure if it matters to the current discussion, but the time to load the source file in the STR was significantly improved by bug 1569829, to around 7 seconds.
There are still two reflows that take place - I think one is caused by measurements performed by CodeMirror.charCoords() in scrollToColumn().
I haven't found a good way around that yet except for using CodeMirror.scrollIntoView() instead, which has different behavior.
Before: https://perfht.ml/3213tDs
After: https://perfht.ml/2IvTLB6

Comment 5

[Maja Frydrychowicz :impossibus (was :maja_zf) (needinfo me)]

(In reply to :Harald Kirschner :digitarald from comment #0)

STR:

1. Open Console on https://www.notion.so/Station-s-public-roadmap-030f47e10b36450f91377035949b51ba?p=6b8d066194de4999acd53b2fb44108b8
2. Follow a log link to app*.js to open it in Debugger

AR: 160s hang on Quantum reference machine. MBP isn't much better.

I can reproduce this today, on Dell XPS, Ubuntu. ~5s hang.

I could not get a hang when opening the file directly from the Debugger sources list, so maybe bug 1553291 helped with that

In contrast, I also get the same length of hang when opening the file directly from the sources list.

Comment 6

[Alexandre Poirot [:ochameau]]

This performance issues no longer exists.