spawn_thread

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool/reaper.rb, line 41
            def spawn_thread(frequency)
              Thread.new(frequency) do |t|
                # Advise multi-threaded app servers to ignore this thread for
                # the purposes of fork safety warnings
                Thread.current.thread_variable_set(:fork_safe, true)
                running = true
                while running
                  sleep t
                  @mutex.synchronize do
                    @pools[frequency].select! do |pool|
                      pool.weakref_alive? && !pool.discarded?
                    end

                    @pools[frequency].each do |p|
                      p.reap
                      p.flush
                    rescue WeakRef::RefError
                    end

                    if @pools[frequency].empty?
                      @pools.delete(frequency)
                      @threads.delete(frequency)
                      running = false
                    end
                  end
                end
              end
            end