Function TestMemStatsEquivalence

prometheus/go_collector_latest_test.go:261–307

(t *testing.T)

}

func TestMemStatsEquivalence(t *testing.T) {
	var msReal, msFake runtime.MemStats
	descs := bestEffortLookupRM(rmNamesForMemStatsMetrics)

	samples := make([]metrics.Sample, len(descs))
	samplesMap := make(map[string]*metrics.Sample)
	for i := range descs {
		samples[i].Name = descs[i].Name
		samplesMap[descs[i].Name] = &samples[i]
	}

	// Force a GC cycle to try to reach a clean slate.
	runtime.GC()

	// Populate msReal.
	runtime.ReadMemStats(&msReal)
	// Populate msFake and hope that no GC happened in between (:
	metrics.Read(samples)

	memStatsFromRM(&msFake, samplesMap)

	// Iterate over them and make sure they're somewhat close.
	msRealValue := reflect.ValueOf(msReal)
	msFakeValue := reflect.ValueOf(msFake)

	typ := msRealValue.Type()
	for i := 0; i < msRealValue.NumField(); i++ {
		fr := msRealValue.Field(i)
		ff := msFakeValue.Field(i)

		if typ.Field(i).Name == "PauseTotalNs" || typ.Field(i).Name == "LastGC" {
			// We don't use those fields for metrics,
			// thus we are not interested in having this filled.
			continue
		}
		switch fr.Kind() {
		// Fields which we are interested in are all uint64s.
		// The only float64 field GCCPUFraction is by design omitted.
		case reflect.Uint64:
			vr := fr.Interface().(uint64)
			vf := ff.Interface().(uint64)
			if float64(vr-vf)/float64(vf) > 0.05 {
				t.Errorf("wrong value for %s: got %d, want %d", typ.Field(i).Name, vf, vr)
			}
		}
	}
}

func TestExpectedRuntimeMetrics(t *testing.T) {
	goMetrics := collectGoMetrics(t, internal.GoCollectorOptions{