redhat-developer / redhat-developer/vscode-xml

High CPU usage in some regular expressions during validation

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TypeScript
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Description

VSCode Version: 1.86.2
Extension: v0.26.1
Windows 10 22H2

Scheme in RelaxNG compact format.

Example of a valid string:

some.text-some-text-{{someText}}-text-{{some_text}}-some-text

When using this regex, the CPU load is about 50%, the waiting time is more than a minute, and no results are obtained:

Identifier = ( xsd:string { pattern="(([A-Za-z][\-.A-Za-z]*)*\{\{[_A-Za-z]+\}\}[\-A-Za-z]*)+" } )

It looks like the problem is in [\-.A-Za-z]*, when simplifying the expression the validation starts to work faster. I did some tests, here are the results:

Identifier = ( xsd:string { pattern="(([a-z][\-a-z]*)*\{\{[_a-z]+\}\}[\-a-z]*)+" } )
# elapsed time: ~1 sec
Identifier = ( xsd:string { pattern="(([_a-z][\-.a-z]*)*\{\{[_a-z]+\}\}[\-_a-z]*)+" } )
# elapsed time: ~7 sec
Identifier = ( xsd:string { pattern="(([A-Za-z][\-A-Za-z]*)*\{\{[_a-z]+\}\}[\-a-z]*)+" } )
# or
Identifier = ( xsd:string { pattern="(([A-Za-z][\-A-Za-z]*)*\{\{[_A-Za-z]+\}\}[\-A-Za-z]*)+" } )
# elapsed time: ~12 sec
Identifier = ( xsd:string { pattern="(([A-Za-z][\-.A-Za-z]*)*\{\{[_A-Za-z]+\}\}[\-A-Za-z]*)+" } )
# elapsed time: over 1 min without result

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the supplied RelaxNG compact pattern in VSCode 1.86.2 with extension v0.26.1 on Windows 10. Compare the reported patterns and timings; done when the valid example is validated without excessive CPU use or a prolonged wait.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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