Ruby Threads + ActiveRecord == "Too Many Connections" ?
Metaprogramming ActiveRecord Connection Pools
Fixing multithreading for Rails in development mode
ActiveRecord Concurrency Currently: Good News and Bad
state of ActiveRecord and concurrency, another update
ActiveRecord Concurrency in Rails4: Avoid leaked connections!
Concurrency and Database Connections in Ruby with ActiveRecord
Connection Management in ActiveRecord
RAILS, ACTIVE RECORD, CONCURRENCY AND SCALING