THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
...
Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]
JIRA: here [Change the link from KAFKA-1 to your own ticket]
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
Motivation
Describe the problems you are trying to solve.
Problem
I am an operator of a Tiered Storage Kafka cluster and I would like to know whether interactions with the remote tier, uploads and deletions, are progressing at a steady pace.
...
| kafka.server:type=BrokerTopicMetrics, name=UploadTierLag, topic=([-.w]+), partition=([-.w]+) | The tier lag of a topic-partition is defined as the number of records in non-active segments eligible for tiering not yet uploaded to the remote storage. |
| kafka.server:type=BrokerTopicMetrics, name=DeleteTierLag, topic=([-.w]+), partition=([-.w]+) | The tier lag of a topic-partition is defined as the number of records in non-active segments marked for deletion but not yet deleted from remote storage. |
Proposed Changes
Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.
Constraints
The metric calculation will should not acquire any locks. If it had to acquire locks then it would be contending with the archival/deletion paths of Tiered Storage.
Reference implementation
Reference implementation for UploadTierLag on topic level: https://github.com/satishd/kafka/commit/c96d3af4d02bf515a4355b14f33793211c5b3745
Details
The metrics for upload and delete will These metrics should not only be updated on every respective an archival and /deletion interval (remote.log.manager.task.interval.ms).
On the archive path of Tiered Storage we go through segments which are eligible for upload in a sequential manner. This allows us to emit the UploadTierLag metric by taking the difference between the segment's base offset and the base offset of the first segment not eligible for tiering.
In a similar manner, when we expire segments from Tiered Storage we go through them in a sequential manner. We can emit the DeleteTierLag metric by taking the difference between the segment's base offset and the end offset + 1 of the last eligible for deletion segmentcycle. If archiving/deletion is failing to run for whatever reason we should still see the latest state of records being queued up for archival/deletion.
Compatibility, Deprecation, and Migration Plan
...
If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.N/A.
- Emit the metrics only on topic level - we rejected this alternative because it wouldn't allow an operator to fairly quickly understand whether any problems are isolated to individual brokers or widespread through the cluster.
- Update the metrics on each archival/deletion cycle - we rejected this alternative because if the cycle does not run for whatever reason the old metric would be emitted even if new segments have become eligible for tiering.