[RF-DOCS] Update Threading and Code Execution Guide [ci skip]

[OughtPuts]

Motivation / Background

This PR has been created to update the Threading and Code Execution Guide as part of the Rails Documentation project.

Detail

The following changes have been made:

• Phrasing and language choices have been updated for improved clarity and simplicity.
• The structure of the guide has been slightly altered to improve flow
• Information about asynchronous Active Record has been added.
• The 'work in progress' label has been removed.
• Examples of wrapped application code have been added.
• Information on Isolated Execution State has been added.
• A section on CurrentAttributes has been added.

Additional information

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Unrelated changes should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

[OughtPuts]

Thanks so much for your clarification comments on the To-Do @p8 - I did have one additional question but I thought it might be easier just to open the PR and then you can consider in context.

For the new CurrentAttributes section, you offered this suggestion:

WARNING: You might be tempted to store state in `Thread.current
yourself, but if you use a threaded server, watch out! Values
aren't automatically deleted after a request and this can
cause bugs.

I was a bit confused by this though, as in the API Documentation it describes:

a thread-isolated attributes singleton, which resets automatically before and after each request

...which would imply automatic deletion? Or am I misunderstanding something somewhere?

Let me know if we need something else added - happy of course to make further changes. Huge thanks!

[bhumi1102]

About half way done

[bhumi1102]

Hi @OughtPuts, Good work getting this guide done! 🎉 The edits do make it more readable!

I'm noticing something about this guide overall (nothing to do with your edits, they are great!), but the subject requires existing knowledge for any of it to make sense. The guide doesn't contain explanations for terms like threads, "parent", "child" process, deadlock. Many terms and concepts are just talked about (e.g. load interlock) without any preamble. Maybe that is okay as this guide is in the "advanced" category. But I'll leave this thought here, in case others have reactions.