Function TestHistogramConcurrency

prometheus/histogram_test.go:155–239

(t *testing.T)

var testBuckets = []float64{-2, -1, -0.5, 0, 0.5, 1, 2, math.Inf(+1)}

func TestHistogramConcurrency(t *testing.T) {
	if testing.Short() {
		t.Skip("Skipping test in short mode.")
	}

	rand.New(rand.NewSource(42))

	it := func(n uint32) bool {
		mutations := int(n%1e4 + 1e4)
		concLevel := int(n%5 + 1)
		total := mutations * concLevel

		var start, end sync.WaitGroup
		start.Add(1)
		end.Add(concLevel)

		his := NewHistogram(HistogramOpts{
			Name:    "test_histogram",
			Help:    "helpless",
			Buckets: testBuckets,
		})

		allVars := make([]float64, total)
		var sampleSum float64
		for i := 0; i < concLevel; i++ {
			vals := make([]float64, mutations)
			for j := 0; j < mutations; j++ {
				v := rand.NormFloat64()
				vals[j] = v
				allVars[i*mutations+j] = v
				sampleSum += v
			}

			go func(vals []float64) {
				start.Wait()
				for _, v := range vals {
					if n%2 == 0 {
						his.Observe(v)
					} else {
						his.(ExemplarObserver).ObserveWithExemplar(v, Labels{"foo": "bar"})
					}
				}
				end.Done()
			}(vals)
		}
		sort.Float64s(allVars)
		start.Done()
		end.Wait()

		m := &dto.Metric{}
		his.Write(m)
		if got, want := int(*m.Histogram.SampleCount), total; got != want {
			t.Errorf("got sample count %d, want %d", got, want)
		}
		if got, want := *m.Histogram.SampleSum, sampleSum; math.Abs((got-want)/want) > 0.001 {
			t.Errorf("got sample sum %f, want %f", got, want)
		}