Redis pub/sub on rails

Question

Following the Redis Pub/Sub

this works fine and i can publish messages in any class using

$redis.publish \'channel\', { object: @object.id }
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Answer 1

The implementation of Redis#subscribe is a loop that will assume control of the current thread in order to listen to events. This means the boot process is halted when dropping a subscription into the context of a Rails class in the way you've shown.

You could try wrapping the call in a thread, but this approach would literally create a new subscription each time this class loaded in a new process, like a rails console or multiple unicorns. Plus, you'd have to be careful about shared state and other threading issues. This is probably not what you want.

You're best off starting a different process that loads the rails environment and subscribes to redis separately from the process(es) serving web requests. It could be a rake task like the following:

namespace :subscribe do
  task :redis => :environment do
    $redis.subscribe("bravo") do |on|
      on.message do |channel, message|
        Rails.logger.info("Broadcast on channel #{channel}: #{message}")
        OtherClass.some_method # yada yada
      end
    end
  end
end