This issue is automatically created based on existing pull request: #39444: Revert change from 42577bc that introduced side effect in ConfigurableWYSIWYGValidator, function validateConfigured()

Description (*)

Commit 42577bc introduced a side effect in validateConfigured() function of ConfigurableWYSIWYGValidator class. validateConfigured() function now permanently modifies allowedTags property with adding/merging ['body', 'html'] to the list of allowed tags on each invocation. This results in an ever growing list of allowed tags for the lifetime of the object of class ConfigurableWYSIWYGValidator.

This hit us really hard since we have some long running PHP processes, that go trough HTML validation, calling validateConfigured() hundred of thousand of times. In the process, allowedTags list grew huge, with an ever increasing size. We saw out PHP process worked increasingly more slow with CPU being at 100% all the time.

Related Pull Requests

Unknown.

Fixed Issues (if relevant)

No reported issue found.

Manual testing scenarios (*)

1. Create a long running PHP process that calls validateConfigured() multiple times. It will run increasingly more slowly.

Questions or comments

No Questions

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• All automated tests passed successfully (all builds are green)