std::atomic<unsigned int> currentJobs{0};

    counter currentJobs{0};
    counter nrStepsDone{0};
    counter totalStepTime{0}; // total time for steps, including closure copying
    counter totalStepBuildTime{0}; // total build time for steps

    time_t startedAt;

    // FIXME: keep stats about aborted steps?

    machine->nrStepsDone++;
    machine->totalStepTime += stepStopTime - stepStartTime;
    machine->totalStepBuildTime += result.stopTime - result.startTime;

        time_t now = time(0);

        root.attr("uptime", now - startedAt);

        root.attr("totalStepTime", totalStepTime);
        root.attr("totalStepBuildTime", totalStepBuildTime);

            root.attr("totalStepTime", totalStepTime);
            root.attr("totalStepBuildTime", totalStepBuildTime);

                nested2.attr("maxJobs", m->maxJobs);

                nested2.attr("nrStepsDone", m->nrStepsDone);
                if (m->nrStepsDone) {
                    nested2.attr("totalStepTime", m->totalStepTime);
                    nested2.attr("totalStepBuildTime", m->totalStepBuildTime);
                    nested2.attr("avgStepTime"); out << (float) m->totalStepTime / m->nrStepsDone;
                    nested2.attr("avgStepBuildTime"); out << (float) m->totalStepBuildTime / m->nrStepsDone;
                }

    startedAt = time(0);