如何减少Ruby / Sinatra应用程序中的Redis连接？ 使用connection_pool？

Question

I have a working Sinatra app that uses redis-namespace for its Redis connections. It works fine, but on Heroku it keeps running out of its 10 Redis connections, despite having very little traffic - they seem to stay open for ages and the app keeps opening new ones.

So, there might be a better way to structure what I've got, so it doesn't keep opening new connections. Or maybe I can use connection_pool ... although I'm not sure how to use that with redis-namespace.

The Sinatra front end ( myapp/frontend.rb ) is something like:

require 'sinatra/base'
require 'myapp/store'

module MyApp
  class Frontend < Sinatra::Base

    registration_store = MyApp::Store::Registration.new
    subscription_store = MyApp::Store::Subscription.new

    get '/' do
      ...
    end

    ...
  end
end

And the Redis-accessing Store classes are in myapp/store.rb :

require 'redis'
require 'redis-namespace'

module MyApp
  module Store
    class RedisBase
      attr_accessor :redis

      def initialize
        uri = URI.parse(ENV['REDISCLOUD_URL'])
        redis = ::Redis.new(:host => uri.host, :port => uri.port, :password => uri.password)

        @redis = ::Redis::Namespace.new(:myapp, :redis => redis)
      end

      class Registration < RedisBase
        def add(user_id)
          redis.sadd(:registrations, user_id)
        end
        ...
      end

      class Subscription < RedisBase
        ...
      end
    end
  end
end

The frontend stores data via the Store classes: registration_store.add(37) .

Am I doing something wrong that keeps opening new connections unnecessarily? Or, how can I add connection_pool or similar?

Answer 1

I bumped into a similar problem and stumbled upon this question. I think you should add redis.quit somewhere in your code. Doing some manual testing monitoring connections with client list on the redis command line gives that the connection disappears on a quit. The object can still be used later and will open a new connection it the connection is closed. No need for pooling! (At least when the load is low.... I guess you may end up with calls not getting a connection under higher loads.)