Generic connection pooling for Ruby.

MongoDB has its own connection pool. ActiveRecord has its own connection pool. This is a generic connection pool that can be used with anything, e.g. Redis, Dalli and other Ruby network clients.


gem install connection_pool


  • Connections are eager created when the pool is created.
  • There is no provision for repairing or checking the health of a connection; connections should be self-repairing. This is true of the dalli and redis clients.


Create a pool of objects to share amongst the fibers or threads in your Ruby application:

@memcached = => 5, :timeout => 5) { }

Then use the pool in your application:

@memcached.with do |dalli|

If all the objects in the connection pool are in use, with will block until one becomes available. If no object is available within :timeout seconds, with will raise a Timeout::Error.

You can use ConnectionPool::Wrapper to wrap a single global connection, making it easier to port your connection code over time:

$redis = => 5, :timeout => 3) { Redis.connect }
$redis.sadd('foo', 1)

The Wrapper uses method_missing to checkout a connection, run the requested method and then immediately check the connection back into the pool. It's not high-performance so you'll want to port your performance sensitive code to use with as soon as possible.

$redis.with do |conn|
  conn.sadd('foo', 1)

Once you've ported your entire system to use with, you can simply remove ::Wrapper and use a simple, fast ConnectionPool.


Mike Perham, @mperham,