Redis + ActionController::Live threads not dying

Question

Background: We\'ve built a chat feature in to one of our existing Rails applications. We\'re using the new ActionController::Live module and ru

Answer 1

Here's a potentially simpler solution which does not use a heartbeat. After much research and experimentation, here's the code I'm using with sinatra + sinatra sse gem (which should be easily adapted to Rails 4):

class EventServer < Sinatra::Base
 include Sinatra::SSE
 set :connections, []
 .
 .
 .
 get '/channel/:channel' do
 .
 .
 .
  sse_stream do |out|
    settings.connections << out
    out.callback {
      puts 'Client disconnected from sse';
      settings.connections.delete(out);
    }
  redis.subscribe(channel) do |on|
      on.subscribe do |channel, subscriptions|
        puts "Subscribed to redis ##{channel}\n"
      end
      on.message do |channel, message|
        puts "Message from redis ##{channel}: #{message}\n"
        message = JSON.parse(message)
        .
        .
        .
        if settings.connections.include?(out)
          out.push(message)
        else
          puts 'closing orphaned redis connection'
          redis.unsubscribe
        end
      end
    end
  end
end

The redis connection blocks on.message and only accepts (p)subscribe/(p)unsubscribe commands. Once you unsubscribe, the redis connection is no longer blocked and can be released by the web server object which was instantiated by the initial sse request. It automatically clears when you receive a message on redis and sse connection to the browser no longer exists in the collection array.