instance method retrieve_connection_pool

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 1150
      def retrieve_connection_pool(spec_name)
        owner_to_pool.fetch(spec_name) do
          # Check if a connection was previously established in an ancestor process,
          # which may have been forked.
          if ancestor_pool = pool_from_any_process_for(spec_name)
            # A connection was established in an ancestor process that must have
            # subsequently forked. We can't reuse the connection, but we can copy
            # the specification and establish a new connection with it.
            establish_connection(ancestor_pool.spec.to_hash).tap do |pool|
              pool.schema_cache = ancestor_pool.schema_cache if ancestor_pool.schema_cache
            end
          else
            owner_to_pool[spec_name] = nil
          end
        end
      end