Audit linter files if they spawn too many processes

(Updated description after analysis)

Based on PR #12105, we should audit other linter files and make sure this pattern does not exist anywhere else i.e disallow spawning of too many processes for each file to be linted, because it’s a bad practice and unnecessarily increases the runtime of lint checks.

Method of Analysis: Not all linter files spawn processes in the above manner, so I started by searching for subprocess keyword in these files to look for this possibility.

• If the keyword is found, I looked at how processes are being created.
• If keyword not found, then I tried to understand on a high level how files are being lint without going into the “logic” part of the linter, and checked for similar behaviour - by looking into their perform_lint_checks or similar functions.

Linter files to be audited (with analysis/PR fixing them):

• codeowner_linter.py - No such pattern found.
• css_linter.py - fixed via #12105
• general_purpose_linter.py - No such pattern found.
• html_linter.py - fixed via #12129
• js_ts_linter.py - Correct pattern already exists. It creates only one process to lint all files as shown below in code: https://github.com/oppia/oppia/blob/1fd68c5a2d1c0c47d44d442455c5fe7e434da633/scripts/linters/js_ts_linter.py#L1121-L1123
• other_files_linter.py - No such pattern found.
• pre_commit_linter.py - No such pattern found.
• python_linter.py - No such pattern found.

[DubeySandeep]

@sajalasati Thanks for sharing the method, it works for all the cases except the python_linter.py as we use linter modules to run pylint/isort checks, can you audit the python_linter file again and update the issue accordingly? 😃

[U8NWXD]

This appears to be done