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: Under Discussion [One of "Under Discussion", "Accepted", "Rejected"]

Discussion thread: here

JIRA: here

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

Motivation

This KIP intends opening the door to implement more effective memory management on Kafka Serializer. Kafka Serializer is used to convert data to a temporary byte[] which is filled into producer/socket buffer. The type of byte array, currently, in Kafka Serializer is pure byte[] so it is hard to reuse the existing byte array for the new messages. Hence, we should introduce an new API to Serializer that enables user to mark the start/end of available bytes in the byte array.

The new response type introduced to Serializer.serialize is ByteBuffer since it comes from java standard library and it is common on NIO code.

The default implementation of new API is based on existent method so binary compatibility is safe. Also, in order to speedup the deprecation cycle, the existent serialize methods are marked as deprecated and all of they get default implementation which throw UnsupportedOperationException. Hence, users who don’t want to extend deprecated methods can migrate to new API safely. Of course, we should not call deprecated serialize methods anymore.

Apart from Serializer, Partitioner also need some updates since it still accept byte[]. The purposed changes are similar to Serializer that we replace byte[] by ByteBuffer. Also, the new API get default implementation based on existent method.

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?

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.