vscode freezes when open specific JSON

[Smoovsky]

• VSCode Version: 1.43.2
• OS Version: win10-x64 1903

Steps to Reproduce:

1. open the JSON file
2. try to interact with the editor a bit (select text, type, etc..)
3. vscode freezes

Does this issue occur when all extensions are disabled?: Yes

The JSON file sizes 2.5MB with moderate complexity.
I tried on two machines with extensions disabled, both were able to reproduce the issue.

Tried:
"editor.largeFileOptimizations": true, "files.maxMemoryForLargeFilesMB": 12288,
didn't help.

Also, it seems that keeping the ".txt" file extension has a better chance to freeze the editor sooner than having ".json" file extension,

Once downgrade back to 1.42.1, the problem is gone and the editor is considerably more responsive (with 1.43.2, the editor was laggy after open the JSON before it crashes).

See the sample JSON:
scrambledJson.txt

[aeschli]

This looks like a general issue with the editor and large file sizes: I can reproduce that even in plain text mode, editing the file is very sluggish.

[davidnich]

possibly related issue: #93310

[alexdima]

I have found this to be caused by bracket matching, specifically the way in which the reverse string is computed. A workaround is to use "editor.matchBrackets": "never".

[roblourens]

I opened the file in insiders and it still hangs

[alexdima]

@roblourens I have tried with VS Code stable (which should be the same version you used for verification), but the file does not freeze for me.

@Smoovsky Can you please verify if opening the file leads to a no longer responding dialog?

[roblourens]

Tried again and got the same result. And this is without editor.matchBrackets or any other settings set.

[Smoovsky]

@alexdima I'm on 1.44.0 now, still able to reproduce this issue:

---

Crash on 1.44.2 as well

[alexdima]

Thank you, after more trying I was able to reproduce too.