instance method shutdown

# File activesupport/lib/active_support/testing/parallelization/server.rb, line 71
        def shutdown
          # Wait for initial queue to drain
          while @distributor.pending?
            sleep 0.1
          end

          @distributor.close

          wait_for_active_workers

          @in_flight.values.each do |(klass, name, reporter)|
            result = Minitest::Result.from(klass.new(name))
            error = RuntimeError.new("result not reported")
            error.set_backtrace([""])
            result.failures << Minitest::UnexpectedError.new(error)
            reporter.synchronize do
              reporter.record(result)
            end
          end
        rescue Interrupt
          warn "Interrupted. Exiting..."

          @distributor.close

          wait_for_active_workers
        end