Welcome to Sidekiq 5.0!

Sidekiq 5.0 contains a reworked job dispatch and execution core to integrate better with the new Rails 5.0 Executor.

What's New

Integrate the job logging and retry logic directly in with the job execution logic in Sidekiq::Processor. Previously this logic was defined as middleware. In Rails 5.0, ActiveSupport::Executor handles ActiveRecord connection management, job callbacks, development mode class loading, etc. Because of its extensive responsibilities, the Executor can't be integrated as Sidekiq middleware; the logging/retry logic had to be pulled out too. Sidekiq 4.2 had a hack to make it work but this redesign provides a cleaner integration. [#3235]
The Delayed Extensions delay, delay_in and delay_until APIs are no longer available by default. The extensions allow you to marshal job arguments as YAML, leading to cases where job payloads could be many 100s of KB or larger if not careful, leading to Redis networking timeouts or other problems. As noted in the Best Practices wiki page, Sidekiq is designed for jobs with small, simple arguments.

Add this line to your initializer to re-enable them and get the old behavior:
```
Sidekiq::Extensions.enable_delay!
```
The old Sidekiq.remove_delay! API has been removed as it is now the default. [#3299]
Sidekiq's quiet signal is now TSTP (think of it as Thread SToP) instead of USR1 as USR1 is not available on JRuby. USR1 will continue to be supported in Sidekiq 5.x for backwards compatibility and will be removed in Sidekiq 6.x. [#3302]
Rails 3.2 is no longer supported.
Ruby 2.0 and Ruby 2.1 are no longer supported. Ruby 2.2.2+ is required.

As always, please upgrade Sidekiq one major version at a time. If you are already running Sidekiq 4.x, then:

gem 'sidekiq', '< 5'

gem 'sidekiq', '< 6'