THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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This page is meant as a template for writing a KIP. To create a KIP choose Tools->Copy on this page and modify with your content and replace the heading with the next KIP number and a description of your issue. Replace anything in italics with your own description.
Status
Current state: [One of "Under Discussion", "Accepted", "Rejected"]
Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]
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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.
We would like to know the progress Tiered Storage is making in uploading and deleting/expiring segments. To achieve this we would like to expose a tier-upload and tier-delete metrics from the point of view of Kafka. Since upload and deletion are carried out by plugins such metrics emitted by Kafka are only going to be best estimates on what it believes the state of the world is. We propose the new metrics to be emitted on per topic and per partition granularity to be able to narrow down which brokers are slow.
We leave more detailed progress metrics to be emitted by the developers of tiered storage plugins.
Public Interfaces
Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.
A public interface is any change to the following:
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Binary log format
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The network protocol and api behavior
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Any class in the public packages under clientsConfiguration, especially client configuration
org/apache/kafka/common/serialization
org/apache/kafka/common
org/apache/kafka/common/errors
org/apache/kafka/clients/producer
org/apache/kafka/clients/consumer (eventually, once stable)
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Monitoring
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Command line tools and arguments
New Metrics
| 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 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. |
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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.
Compatibility, Deprecation, and Migration Plan
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Reference implementation for UploadTierLag on topic level: https://github.com/satishd/kafka/commit/c96d3af4d02bf515a4355b14f33793211c5b3745
If we have 10 closed segments ready for upload the UploadTierLag will start as the sum of offsets in these 10 segments and as segments are uploaded we will decrease the lag by decrementing it for each segment we have issued an upload for.
Similarly, if we have 10 segments which have breached their retention the DeleteTierLag will start as the sum of offsets in these 10 segments and as segments are deleted we will decrease the lag by decrementing it for each segment we have issued a delete for.
Compatibility, Deprecation, and Migration Plan
These are new metrics and as such shouldn't have compatibility concerns.
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Test Plan
Describe in few sentences how the KIP will be tested. We are mostly interested in system tests (since unit-tests are specific to implementation details). How will we know that the implementation works as expected? How will we know nothing broke?
Unit and integration tests.
Rejected Alternatives
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