vmalert: reduce allocations for Prometheus resp parse (#3435)

Method `metrics()` now pre-allocates slices for labels
and results from query responses. This reduces the number 
of allocations on the hot path for instant requests.

Signed-off-by: hagen1778 <roman@victoriametrics.com>
This commit is contained in:
Roman Khavronenko 2022-12-05 08:34:54 +01:00 committed by Aliaksandr Valialkin
parent 9ac1174493
commit a922308438
No known key found for this signature in database
GPG key ID: A72BEC6CD3D0DED1
4 changed files with 70 additions and 17 deletions

View file

@ -54,6 +54,19 @@ func (m *Metric) SetLabel(key, value string) {
m.AddLabel(key, value)
}
// SetLabels sets the given map as Metric labels
func (m *Metric) SetLabels(ls map[string]string) {
var i int
m.Labels = make([]Label, len(ls))
for k, v := range ls {
m.Labels[i] = Label{
Name: k,
Value: v,
}
i++
}
}
// AddLabel appends the given label to the label set
func (m *Metric) AddLabel(key, value string) {
m.Labels = append(m.Labels, Label{Name: key, Value: value})

View file

@ -32,19 +32,17 @@ type promInstant struct {
}
func (r promInstant) metrics() ([]Metric, error) {
var result []Metric
result := make([]Metric, len(r.Result))
for i, res := range r.Result {
f, err := strconv.ParseFloat(res.TV[1].(string), 64)
if err != nil {
return nil, fmt.Errorf("metric %v, unable to parse float64 from %s: %w", res, res.TV[1], err)
}
var m Metric
for k, v := range r.Result[i].Labels {
m.AddLabel(k, v)
}
m.SetLabels(res.Labels)
m.Timestamps = append(m.Timestamps, int64(res.TV[0].(float64)))
m.Values = append(m.Values, f)
result = append(result, m)
result[i] = m
}
return result, nil
}

View file

@ -0,0 +1,20 @@
package datasource
import (
"encoding/json"
"testing"
)
func BenchmarkMetrics(b *testing.B) {
payload := []byte(`[{"metric":{"__name__":"vm_rows"},"value":[1583786142,"13763"]},{"metric":{"__name__":"vm_requests", "foo":"bar", "baz": "qux"},"value":[1583786140,"2000"]}]`)
var pi promInstant
if err := json.Unmarshal(payload, &pi.Result); err != nil {
b.Fatalf(err.Error())
}
b.Run("Instant", func(b *testing.B) {
for i := 0; i < b.N; i++ {
_, _ = pi.metrics()
}
})
}

View file

@ -7,6 +7,7 @@ import (
"net/http/httptest"
"net/url"
"reflect"
"sort"
"strconv"
"strings"
"testing"
@ -74,7 +75,7 @@ func TestVMInstantQuery(t *testing.T) {
case 5:
w.Write([]byte(`{"status":"success","data":{"resultType":"matrix"}}`))
case 6:
w.Write([]byte(`{"status":"success","data":{"resultType":"vector","result":[{"metric":{"__name__":"vm_rows"},"value":[1583786142,"13763"]},{"metric":{"__name__":"vm_requests"},"value":[1583786140,"2000"]}]}}`))
w.Write([]byte(`{"status":"success","data":{"resultType":"vector","result":[{"metric":{"__name__":"vm_rows","foo":"bar"},"value":[1583786142,"13763"]},{"metric":{"__name__":"vm_requests","foo":"baz"},"value":[1583786140,"2000"]}]}}`))
case 7:
w.Write([]byte(`{"status":"success","data":{"resultType":"scalar","result":[1583786142, "1"]}}`))
}
@ -115,19 +116,17 @@ func TestVMInstantQuery(t *testing.T) {
}
expected := []Metric{
{
Labels: []Label{{Value: "vm_rows", Name: "__name__"}},
Labels: []Label{{Value: "vm_rows", Name: "__name__"}, {Value: "bar", Name: "foo"}},
Timestamps: []int64{1583786142},
Values: []float64{13763},
},
{
Labels: []Label{{Value: "vm_requests", Name: "__name__"}},
Labels: []Label{{Value: "vm_requests", Name: "__name__"}, {Value: "baz", Name: "foo"}},
Timestamps: []int64{1583786140},
Values: []float64{2000},
},
}
if !reflect.DeepEqual(m, expected) {
t.Fatalf("unexpected metric %+v want %+v", m, expected)
}
metricsEqual(t, m, expected)
m, req, err := pq.Query(ctx, query, ts) // 7 - scalar
if err != nil {
@ -158,13 +157,36 @@ func TestVMInstantQuery(t *testing.T) {
if len(m) != 1 {
t.Fatalf("expected 1 metric got %d in %+v", len(m), m)
}
exp := Metric{
Labels: []Label{{Value: "constantLine(10)", Name: "name"}},
Timestamps: []int64{1611758403},
Values: []float64{10},
exp := []Metric{
{
Labels: []Label{{Value: "constantLine(10)", Name: "name"}},
Timestamps: []int64{1611758403},
Values: []float64{10},
},
}
if !reflect.DeepEqual(m[0], exp) {
t.Fatalf("unexpected metric %+v want %+v", m[0], expected)
metricsEqual(t, m, exp)
}
func metricsEqual(t *testing.T, gotM, expectedM []Metric) {
for i, exp := range expectedM {
got := gotM[i]
gotTS, expTS := got.Timestamps, exp.Timestamps
if !reflect.DeepEqual(gotTS, expTS) {
t.Fatalf("unexpected timestamps %+v want %+v", gotTS, expTS)
}
gotV, expV := got.Values, exp.Values
if !reflect.DeepEqual(gotV, expV) {
t.Fatalf("unexpected values %+v want %+v", gotV, expV)
}
sort.Slice(got.Labels, func(i, j int) bool {
return got.Labels[i].Name < got.Labels[j].Name
})
sort.Slice(exp.Labels, func(i, j int) bool {
return exp.Labels[i].Name < exp.Labels[j].Name
})
if !reflect.DeepEqual(exp.Labels, got.Labels) {
t.Fatalf("unexpected labels %+v want %+v", got.Labels, exp.Labels)
}
}
}