Mongoid Connection Pool

If you ever use Mongoid in a threaded environment such as Sidekiq with Rubinius or JRuby you will quickly find out that Mongoid does not handle DB connections well.

Mongoid by default gives every thread it's own database connection and doesn't clean up after itself, so these connections remain open. MongoDB will quickly become overloaded and you will no longer be able to connect. Often times MongoDB itself will also crash.

This gem monkey patches Mongoid (>= 3.1 < 4.0) to add connection pooling. We take over how Mongoid handles it's connections, so there is nothing you need to do to take advantage of it.

This was originally submitted as a PR to the Mongoid project but was turned down since Moped 2.0(MongoDB database driver used by Mongoid) includes it's own implementation of connection pooling. This is all well and good but it is still as of yet to be released, and won't be supported on Mongoid versions < 4.0 (also unreleased).

This monkey patch passes all of Mongoid's specs.

Add this line to your application's Gemfile:

gem 'mongoid_connection_pool'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mongoid_connection_pool

Just require mongoid_connection_pool AFTER Mongoid. That's it. Easy-peasy.

Configure it for your environment with the following options:
session_pool_size: The max number of DB connections you want to have in the pool
session_checkout_timeout: Time for a thread to wait for a connection (in seconds) before timing out
session_reap_frequency: Time, in seconds, for the session to reap unused but checked out sessions

Mongoid.configure do |config|
    config.session_pool_size = 5
    config.session_checkout_timeout = 3
    config.session_reap_frequency = 3
end

You can also take advantage of Mongoid.with_session method. This is similar to ActiveRecords 'with_connection'

Mongoid.with_session do
  # stuff
end

With this you are explicitly checking out a connection and checking it back in once complete.

You also no longer need to use Kiqstand, the Sidekiq Middleware for Mongoid.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request