Tag: kafka

Karafka framework 2.0 announcement

August 9, 2022 / / 0 Comments

I'm thrilled to announce the new and shiny Karafka 2.0. It is an effect of my work of almost four years.

For those who wonder what Karafka is, Karafka is a Ruby and Rails multi-threaded efficient Kafka processing framework.

Karafka 2.0 is a major rewrite that brings many new things to the table but removes specific concepts that were not as good as I initially thought when I created them.

In this announcement article, I will describe the most noticeable features and improvements that got into this release. If you are interested in a more comprehensive list, you can find it here.

Note: Upgrade notes for migration from Karafka 1.4 to Karafka 2.0 can be found here.

Getting started

If you are new to Karafka and want to play around, follow this demo or visit the Getting Started page:

Noticeable features and improvements

This section includes all the noticeable changes you may be interested in if you already work with Karafka or if you want to understand the journey.

Multi-threading

Most of the engineering work around this release was about performance, scalability, and improvement of the overall engineering experience.

Multi-threading is probably the most significant change in Karafka since it was created. Up until now, Karafka was single-threaded. That means that any concurrency would have to be implemented by the end user. The reason is dead simple: concurrency is hard. Synchronization is hard. Warranties are hard. I do feel (and can back it up with integration specs) that I tackled it pretty well.

Karafka 2.0 uses native Ruby threads to achieve concurrent processing in three scenarios:

  • for concurrent processing of messages from different topics partitions.
  • for concurrent processing of messages from a single partition when using the Virtual Partitions feature.
  • to handle consumer groups management (each consumer group defined will be managed by a separate thread)

This can bring big advantages when any IO is involved.

When you start consuming messages, Karafka will fetch and distribute data to utilize multiple threads while preserving all the Kafka ordering warranties.

Years ago, I developed a lot of in-app async code to bypass Karafka limitations, and it makes me extremely happy to be able to retire all of it.

But wait, there's more...

Virtual Partitions

Virtual Partitions allow you to parallelize the processing of data from a single partition. This can drastically increase throughput when IO operations are involved.

While the default scaling strategy for Kafka consumers is to increase partitions count and number of consumers, in many cases, this will not provide you with desired effects. In the end, you cannot go with this strategy beyond assigning one process per single topic partition. That means that without a way to parallelize the work further, IO may become your biggest bottleneck.

Virtual Partitions solve this problem by providing you with the means to further parallelize work by creating "virtual" partitions that will operate independently but will obey all the Kafka warranties as a collective processing unit.

topic :orders_states do
  consumer OrdersStatesConsumer
  # Distribute work to virtual partitions based on the user id
  virtual_partitions(
    partitioner: ->(message) { message.payload[:user_id] }
  )
end

With Virtual Partitions, you benefit from both worlds: scaling with Kafka partitions and scaling with Ruby threads.

*This example illustrates the throughput difference for IO intense work, where the IO cost of processing a single message is 1ms.

Active Job support

Active Job is a standard interface for interacting with job runners in Ruby on Rails. Active Job can be configured to work with Karafka.

While Kafka is not a message queue, I still decided to create an Active Job adapter for it. Why? Because ordered jobs are something, I always wished for Ruby on Rails to have. On top of that, you may already have Kafka and only a few jobs to run. If so, why not use it and save yourself a hustle of yet another tool to maintain?

class Application < Rails::Application
  # ...
  config.active_job.queue_adapter = :karafka
end

End-to-end integration test suite

Karafka comes with a home-brew framework for running end-to-end integration specs against Kafka. I did my best to describe every possible case I could have imagined to ensure that the framework behaves as expected under any circumstances.

It is also a great place to learn about how Karafka behaves in particular scenarios.

Lower supply chain fingerprint

The number of external dependencies Karafka relies on has been reduced significantly. It was done to ensure that Karafka can be integrated into and upgraded in applications without causing dependency conflicts.

Upgraded documentation

Karafka and WaterDrop have been fully updated with several new sections describing use-cases, edge-cases and providing help and suggestions for both simple and advanced usage.

Out-of-the-box DataDog and StatsD instrumentation

Using DataDog or StatsD? In just a few lines you can enable full instrumentation of both consumption and production of messages:

# initialize the listener with statsd client
dd_listener = ::Karafka::Instrumentation::Vendors::Datadog::Listener.new do |config|
  config.client = Datadog::Statsd.new('localhost', 8125)
  # Publish host as a tag alongside the rest of tags
  config.default_tags = ["host:#{Socket.gethostname}"]
end

# Subscribe with your listener to Karafka and you should be ready to go!
Karafka.monitor.subscribe(dd_listener)

License change

Karafka 2.0 is dual licensed under LGPL and a Commercial License. Depending on your use-case, you should be good with one or the other.

Note: Before the license change, I did obtain the consent of all the contributors for a re-license. I want to say thank you to each of you for allowing me to do so.

Seamless Ruby on Rails integration

Karafka always had good integration with Ruby on Rails. With the 2.0 release, however, this integration is elevated to another level: no more files editing, no more configuration copying. Everything works out of the box.

Karafka Pro

This release is the first release that includes a Pro subscription.

Building a complex and reliable open-source is neither easy nor fast. Many companies rely on Karafka, and following Mikes Perham advice I have decided to introduce the Pro subscription to be able to support the further development of the ecosystem.

Karafka Pro has many valuable, well-documented, well-tested functionalities that can significantly improve your day-to-day operations with Kafka in Ruby. It also introduces commercial support, as due to a sheer number of questions and requests, I do need to have a way to prioritize those.

SInce it's not only me, 10% of the income will be further distributed down the supply chain pipeline to support the work of people I rely on.

Help me build and maintain a high-quality Kafka ecosystem for Ruby and Ruby on Rails.

Buy Karafka Pro.

Karafka 1.4 maintenance

With this release an official EOL policies have been introduced. Karafka 1.4 will be supported until the end of February 2023.

Karafka 2.0 has a lower dependency fingerprint and is in everything 1.4 was not. I strongly encourage you to upgrade.

What's ahead

Many things. This release is just the beginning. I am already working on a 2.1 release that will include several great additions, including:

  • Management Web-UI similar to the one Resque and Sidekiq have
  • Producer transactions
  • At Rest encryption
  • CurrentAttributes support for ActiveJob
  • Seamless Dead-Letter Queue integration

Upgrade notes

Upgrade notes for migration from Karafka 1.4 to Karafka 2.0 can be found here.

References

Stay tuned and don't forget to join our Slack channel.

Karafka framework 1.4.0 Release Notes (Ruby + Kafka)

September 5, 2020 / / 0 Comments

This release mostly solves problems related to message deserialization and normalizes some of the naming conventions to ease during the upgrade to the upcoming 2.0 version.

Note: This release is the last release with ruby-kafka under the hood. We've already started the process of moving to rdkafka-ruby.

Note: If you are using Sidekiq-Backend plugin, please make sure that you've processed all the jobs from your Sidekiq queue before upgrading Karafka gems.

Changes (features, incompatibilities, etc)

consumer#metadata is now consumer#batch_metadata

This change is trivial: if you use batch consuming mode and you use the Consumer#metadata method, replace it with Consumer#batch_metadata.

# Karafka 1.3
class UsersConsumer < ApplicationConsumer
  def consume
    puts metadata
  end
end

# Karafka 1.4
class UsersConsumer < ApplicationConsumer
  def consume
    puts batch_metadata
  end
end

Message metadata available under #metadata method

Up to version 1.3, all the message metadata would be directly available under the root scope of the params object using both direct method reference as well as with #[] accessor.

While it felt like "The Rails way", it had several side-effects, amongst which the biggest were the need of having a hash like API, issues with accessing metadata without payload deserialization, and a lack of clear separation between payload and the metadata.

From now on, you can use the params.metadata object to fetch all the metadata.

Note: we've preserved the direct metadata values fetching from the params object to preserve backwards compatibility.

# 1.3
params['partition'] #=> 0
params.partition #=> 0

# 1.4
params['partition'] #=> NoMethodError (undefined method '[]')

# This will work due to backward compatibility
params.partition #=> 0

# This is the recommended way of accessing metadata
params.metadata.partition #=> 0

# This will also work as metadata is a struct now
params.metadata[:partition] #=> 0
params.metadata['partition'] #=> 0

Message metadata access allowed without message deserialization

When accessing metadata, the payload is not being deserialized until #payload method is being used.

null message support in the default JSON deserializer

When the Kafka message payload is null / nil, deserialization won't fail. Support for it was added as some of the Karafka users use log compaction with a nil payload. In case like that, #payload will return nil.

Karafka::Params::Params no longer inherits from a Hash

Karafka::Params::Params is now just a struct. This change is introduced to normalize the setup, limit the corner cases and simplify the interface only to methods that are really needed.

Documentation

Our Wiki has been updated accordingly to the 1.4 status. Please notify us if you find any incompatibilities.

Getting started with Karafka

If you want to get started with Kafka and Karafka as fast as possible, then the best idea is to just clone our example repository:

git clone https://github.com/karafka/example-app ./example_app

then, just bundle install all the dependencies:

cd ./example_app
bundle install

and follow the instructions from the example app Wiki.

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