Do not clear cache when running eager tasks

[jcohen28]

Description

When the CELERY_ALWAYS_EAGER setting variable is True celery tasks are run in the same thread as the Django Request. As a result, code that is intended to cleanup the celery worker inadvertently clears the RequestCache.

**Update: ** There are times in which we may want to run celery eagerly and still clear the cache, such as testing. I have reverted the logic in _clear_request_cache back to only check CLEAR_REQUEST_CACHE_ON_TASK_COMPLETION as original, and instead have set CLEAR_REQUEST_CACHE_ON_TASK_COMPLETION = False in all dev and test environments that already have CELERY_ALWAYS_EAGER = True. The unit test that specifically tests whether the request cache is getting cleared upon completion of a celery task then overrides CLEAR_REQUEST_CACHE_ON_TASK_COMPLETION = True even though CELERY_ALWAYS_EAGER = True for the sake of that specific testing purpose.

Supporting information

The issue and its resolution are discussed here.

Testing instructions

Run the platform using the devstack/test/bokchoy settings files, or simply defining CELERY_ALWAYS_EAGER = True. Confirm that the RequestCache is not cleared each time a celery task is triggered with apply_sync.

Deadline

None

Other information

None

[openedx-webhooks]

Thanks for the pull request, @jcohen28! Please note that it may take us up to several weeks or months to complete a review and merge your PR.

Feel free to add as much of the following information to the ticket as you can:

• supporting documentation
• Open edX discussion forum threads
• timeline information ("this must be merged by XX date", and why that is)
• partner information ("this is a course on edx.org")
• any other information that can help Product understand the context for the PR

All technical communication about the code itself will be done via the GitHub pull request interface. As a reminder, our process documentation is here.

Please let us know once your PR is ready for our review and all tests are green.

[openedx-webhooks]

@jcohen28 Even though your pull request wasn’t merged, please take a moment to answer a two question survey so we can improve your experience in the future.