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Status

Current state: Canceled in favor of KIP 831

There is a duplicate KIP that is already adopted which is doing the same thing as this KIP proposes. Reference: KIP-831


Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]

JIRA: here

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

When a Kafka broker process starts up, it goes through the process of restoring the state of the broker based on the segment files stored on the disk and other auxiliary checkpoint files used to store the broker's state. 

In a clean shutdown scenario, Kafka undergoes a clean shutdown, meaning all states are persisted on the local disk, and the process of restoring the broker's state is relatively quick (estimated under 10 minutes for a partition count of 4000).

However, if the broker experiences an unclean shutdown, the log loading process will also involve recovering the broker state by replaying messages and trying to reconstruct the last known safe state of the broker. This recovery process can take a very long time. Anecdotal data shows we have seen processes that took more than two hours.

Log recovery is triggered as part of log loading, during this recovery process, there is no metric that indicates the progress, leaving both Kafka cluster administrators and customers blind to the state of the recovery. Not having any metric that operators can use to estimate the ETA is difficult for planning and managing expectations.


The motivation for this KIP is to provide a metrics that shows the progress of log loading when a broker starts up.


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:

  • Binary log format

  • The network protocol and api behavior

  • 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)

  • Monitoring

  • Command line tools and arguments

  • Anything else that will likely break existing users in some way when they upgrade

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

  • What impact (if any) will there be on existing users?
  • If we are changing behavior how will we phase out the older behavior?
  • If we need special migration tools, describe them here.
  • When will we remove the existing behavior?

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?

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.

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