Metered - difference between Prometheus and JSON format

[rsvoboda]

There are differences in reported results between Prometheus and JSON format.
When using the same deployment with OpenLiberty there are no differences in reported results between Prometheus and JSON format.

Code:

    @Metered(name = "itemsSold",
            unit = MetricUnits.MINUTES,
            description = "Metrics to monitor sold method - @Metered.",
            absolute = true)
    @GET
    @Path("/sold")
    public Response itemSold() {
        return Response.ok().build();
}

SmallRye Metrics via WF:

$ curl http://127.0.0.1:9990/metrics/application/itemsSold -H "Accept: application/json"
{  "itemsSold" : {
    "count": 2,
    "meanRate": 0.04008729595250973,
    "oneMinRate": 0.10268342380651845,
    "fiveMinRate": 0.1750346638085895,
    "fifteenMinRate": 0.19130574782060583
  }}

$ curl http://127.0.0.1:9990/metrics/application/itemsSold 2>/dev/null | grep -v TYPE | grep -v HELP
application:items_sold_total 120.0
application:items_sold_rate_per_second 2.394402679418024
application:items_sold_one_min_rate_per_second 6.6278656573403
application:items_sold_five_min_rate_per_second 10.526838271241285
application:items_sold_fifteen_min_rate_per_second 11.481234917949807

OpenLiberty:

curl https://localhost:9443/metrics/application/itemsSold -H "Accept: application/json" --insecure -u theUser:thePassword 2>/dev/null | jq
{
  "itemsSold": {
    "fiveMinRate": 0.1934432200964012,
    "fifteenMinRate": 0.19779007785878447,
    "meanRate": 0.12195642084943523,
    "count": 2,
    "oneMinRate": 0.16929634497812282
  }
}

$ curl https://localhost:9443/metrics/application/itemsSold --insecure -u theUser:thePassword 2>/dev/null | grep -v TYPE | grep -v HELP
application:items_sold_total 2
application:items_sold_rate_per_second 0.12012122656287032
application:items_sold_one_min_rate_per_second 0.16929634497812282
application:items_sold_five_min_rate_per_second 0.1934432200964012
application:items_sold_fifteen_min_rate_per_second 0.19779007785878447

Code: https://github.com/rsvoboda/rsvoboda-playground/blob/master/microprofile-metrics-hello-prometheus/src/main/java/com/sebastian_daschner/hello_prometheus/CoffeesResource.java#L47

[jmartisk]

This should be fixed for 1.1.3 through #48
By the way, I think unit = MetricUnits.MINUTES, in your code example does not make sense, the spec says that

Meter and Timer have fixed units as described below regardless of the unit value in the Metadata.

[rsvoboda]

So unit gets ignored ?

[jmartisk]

Yes. Meter computes the rates always in PER_SECOND unit (and the total is dimension-less)

[jmartisk]

The bug was basically that the unit was not completely ignored when it should have been, leading to nonsensical unit conversions for the output.