A connection pool leak in a Rails application was traced back to the logger holding onto a database connection due to the accidental passing of an ActiveRecord relation, which evaluated within a thread causing connection exhaustion. The resolution involved modifying the logging to only include primitive values and highlighted the importance of careful logging practices and monitoring connection usage.

AmazingPrint is a Ruby library that enhances the pretty-printing of Ruby objects with full color and proper indentation, making it a suitable replacement for the now-stale AwesomePrint. It supports Rails ActiveRecord objects and includes customizable options for formatting output, including the ability to log formatted data and use it within Rails templates. Installation is straightforward via Ruby gem or cloning the repository from GitHub.