Investigate additional mitigations to cache invalidation issues
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- Dominant language
- Python
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Description
Author: @dralley (dalley)
Redmine Issue: 9079, https://pulp.plan.io/issues/9079
If Redis goes down, Pulp can no longer invalidate / clear out the cache appropriately while it is offline, and when it comes back up it will be out of date.
Additionally there could be smaller transient errors that prevent invalidation events from going through.
The time window this damage can manifest is pretty small (10 minutes as of #8996) but we should investigate further methods of mitigation. One example could be - pulpcore detecting when the Redis connection has failed, and either retrying cache invalidations, or flushing the cache entirely.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
No file or test is named. Start by reviewing the cache invalidation behavior around Redis failures and the changes referenced in #8996, then examine transient invalidation errors and recovery after Redis returns. Done means identifying and evaluating a concrete mitigation for stale cache state.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python, redis
- Domain
- backend
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100