spawn_thread

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 334
            def spawn_thread(frequency)
              Thread.new(frequency) do |t|
                loop do
                  sleep t
                  @mutex.synchronize do
                    @pools[frequency].select!(&:weakref_alive?)
                    @pools[frequency].each do |p|
                      p.reap
                      p.flush
                    rescue WeakRef::RefError
                    end
                  end
                end
              end
            end