[cbartz]

Applicable spec:

Overview

Use multithreading instead of multiprocessing

Rationale

multiprocessing is more costly in terms of memory. The charm might spawn way more runners than currently in the future once it is able to spawn runners for different openstack flavors,images, etc. In order to support this usecase, we remove the multiprocessing part.

Checklist

• The charm style guide was applied.
• The contributing guide was applied.
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation for charmhub is updated.
• The PR is tagged with appropriate label (urgent, trivial, complex).
• The changelog is updated with changes that affects the users of the charm.
• The application version number is updated in github-runner-manager/pyproject.toml.

No direct user impact (except fewer resource usage).

[Copilot]

Pull Request Overview

This PR switches from multiprocessing to multithreading for spawning runners to reduce memory usage. The change anticipates future scaling needs where the charm may spawn many more runners across different OpenStack flavors and images.

• Replaced multiprocessing.Pool with multiprocessing.pool.ThreadPool
• Updated version number from 0.6.2 to 0.6.3

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
github-runner-manager/src/github_runner_manager/manager/runner_manager.py	Switched from Process Pool to Thread Pool for runner spawning
github-runner-manager/pyproject.toml	Bumped version number to reflect the change

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