How do I create labeled metrics with different labels in a threaded environment?

[Derek Chadwell]

I have an application that spawns many worker threads.  In the main application I create a PrometheusMetrics() helper class that registers the metrics the threads will report on with the appropriate label names.  I pass the PrometheusMetrics class into each thread, and then create local variables in each thread with the labels filled out differently per thread.

I start the server and I see the #HELP and #TYPE text per metric I've registered, but I don't see any of the metrics outputs.

class PrometheusMetrics() {

    lateinit var iterations = Counter.build()

         .name("a_metric")

        .labelNames("a","b","c")
          .help("some help")

}

class main(){

 prometheusMetrics =PrometheusMetrics()

    forEach (iterator){

        spawnWorker(prometheusMetrics)

    }

}

Worker(prometheusMetrics: PrometheusMetrics){

    val localMetric = prometheusMetrics.iterations.labels('different","per","worker")

     localMetric.inc()

}

Is there something fundamentally wrong with this approach?

Thanks,

Derek