Resolve failures pauseless ingestion draft #4
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…auseless ingestion in RealtimeSegmentValidationManager
…d by RealtimeSegmentValitdationManager to fix commit protocol failures
…g commit protocol
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Pauseless Ingestion Failure Resolution
Please refer to PR: apache#14741 for happy path. This PR aims to only cover the failure scenarios. Once the above one is merged a better diff covering only failures will be visible.
To view only diff covering failure scenarios, for the time being, refer to:
Summary
This PR aims to provide ways to resolve the failure scenarios that we can encounter during pauseless ingestion. The detailed list of failure scenarios can be found here: link along with the failure handling strategies: link
Following sequence diagrams summarizes the failure scenarios and the resolution.
Failure Scenarios & Resolution Approaches
Failures encountered during the commit protocol can be categorized into two types: recoverable and unrecoverable failures.
Recoverable failures are those in which at least one of the servers retains the segment on disk.
Unrecoverable failures occur when none of the servers have the segment on disk.
Recoverable Failures
Recoverable failures will be addressed through RealtimeSegmentValidationManager. This approach will handle scenarios such as upload failures and incomplete commit protocol executions.
The controller or server can run into issues in between any of the steps of the commit protocol as listed below:
Request Type: COMMIT_START
Request Type: COMMIT_END_METADATA
4. Update Segment ZK metadata for the committing segment (seg__0__0):
- Change status to DONE.
- Update deepstore url.
- Any additional metadata.
The RealtimeSegmentValidationManager figures out which step of the commit protocol failed and how can it be fixed. This is very similar to how commit protocol failures were handled before with some minor changes.
Non-recoverable Failures
These failures require ingesting the segment again from upstream, followed by build, upload and ZK metadata update.