Upgrading to Sidekiq Pro 2.0

Sidekiq Pro 2.0 allows nested batches for more complex job workflows and provides a new reliable scheduler which uses Lua to guarantee atomicity and much higher performance.

It also removes deprecated APIs, changes the batch data format and how features are activated. Read carefully to ensure your upgrade goes smoothly.

Sidekiq Pro 2.0 requires Sidekiq 3.3.2 or greater. Redis 2.8 is recommended; Redis 2.4 or 2.6 will work but some functionality will not be available.

Note that you CANNOT go back to Pro 1.x once you've created batches with 2.x. The new batches will not process correctly with 1.x.

If you are on a version of Sidekiq Pro <1.5, you should upgrade to the latest 1.x version and run it for a week before upgrading to 2.0.

Nested Batches

Batches can now be nested within the jobs method. This feature enables Sidekiq Pro to handle workflow processing of any size and complexity!

a = Sidekiq::Batch.new
a.on(:success, SomeCallback)
a.jobs do
  SomeWork.perform_async

  b = Sidekiq::Batch.new
  b.on(:success, MyCallback)
  b.jobs do
    OtherWork.perform_async
  end
end

Parent batch callbacks are not processed until all child batch callbacks have run successfully. In the example above, MyCallback will always fire before SomeCallback because b is considered a child of a.

Of course you can dynamically add child batches while a batch job is executing.

def perform(*args)
  do_something(args)

  if more_work?
    # Sidekiq::Worker#batch returns the Batch this job is part of.
    batch.jobs do
      b = Sidekiq::Batch.new
      b.on(:success, MyCallback)
      b.jobs do
        OtherWork.perform_async
      end
    end
  end
end

More context: [#1485]

Batch Data

The batch data model was overhauled. Batch data should take significantly less space in Redis now. A simple benchmark shows 25% savings but real world savings should be even greater.

Batch 2.x BIDs are 14 character URL-safe Base64-encoded strings, e.g. "vTF1-9QvLPnREQ". Batch 1.x BIDs were 16 character hex-encoded strings, e.g. "4a3fc67d30370edf".
In 1.x, batch data was not removed until it naturally expired in Redis. In 2.x, all data for a batch is removed from Redis once the batch has run any success callbacks.
Because of the former point, batch expiry is no longer a concern. Batch expiry is hardcoded to 30 days and is no longer user-tunable.
Failed batch jobs no longer automatically store any associated backtrace in Redis.

There's no data migration required. Sidekiq Pro 2.0 transparently handles both old and new format.

More context: [#2130]

Reliability

2.0 brings a new reliable scheduler which uses Lua inside Redis so enqueuing scheduled jobs is atomic. Benchmarks show it 50x faster when enqueuing lots of jobs.

Two caveats:

Client-side middleware is not executed for each job when enqueued with the reliable scheduler. No Sidekiq or Sidekiq Pro functionality is affected by this change but some 3rd party plugins might be.
The Lua script used inside the reliable scheduler is not safe for use with Redis Cluster, Redis Sentinel or other distributed Redis solutions. It is safe to use with a typical master/slave replication setup.

You no longer require anything to use the Reliability features.

Activate reliable fetch and/or the new reliable scheduler:

Sidekiq.configure_server do |config|
  config.reliable_fetch!
  config.reliable_scheduler!
end

Activate reliable push:

Sidekiq::Client.reliable_push!

More context: [#2130]

Other Changes

You must require sidekiq/pro/notifications if you want to use the existing notification schemes. I don't recommend using them as the newer-style Sidekiq::Batch#on method is simpler and more flexible.
Several classes have been renamed. Generally these classes are ones you should not need to require/use in your own code, e.g. the Batch middleware.
You can add attr_accessor :jid to a Batch callback class and Sidekiq Pro will set it to the jid of the callback job. [#2178]
There's now an official API to iterate all known Batches [#2191]

Sidekiq::BatchSet.new.each {|status| p status.bid }

The Web UI now shows the Sidekiq Pro version in the footer. [#1991]

Thanks

Adam Prescott, Luke van der Hoeven and Jon Hyman all provided valuable feedback during the release process. Thank you guys!

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