diff --git a/README.md b/README.md
index d126a4861..084367ee3 100644
--- a/README.md
+++ b/README.md
@@ -1425,7 +1425,7 @@ In this case VictoriaMetrics puts query trace into `trace` field in the output J
 For example, the following command:
 
 ```bash
-curl http://localhost:8428/api/v1/query_range -d 'query=2*rand()' -d 'start=-1h' -d 'step=1m' -d 'trace=1' | jq -r '.trace'
+curl http://localhost:8428/api/v1/query_range -d 'query=2*rand()' -d 'start=-1h' -d 'step=1m' -d 'trace=1' | jq '.trace'
 ```
 
 would return the following trace:
diff --git a/app/vmselect/main.go b/app/vmselect/main.go
index 87e205ef5..2ff484b51 100644
--- a/app/vmselect/main.go
+++ b/app/vmselect/main.go
@@ -93,7 +93,7 @@ func RequestHandler(w http.ResponseWriter, r *http.Request) bool {
 	startTime := time.Now()
 	defer requestDuration.UpdateDuration(startTime)
 	tracerEnabled := searchutils.GetBool(r, "trace")
-	qt := querytracer.New(tracerEnabled)
+	qt := querytracer.New(tracerEnabled, r.URL.Path)
 
 	// Limit the number of concurrent queries.
 	select {
diff --git a/app/vmselect/netstorage/netstorage.go b/app/vmselect/netstorage/netstorage.go
index 533c85aff..86046011f 100644
--- a/app/vmselect/netstorage/netstorage.go
+++ b/app/vmselect/netstorage/netstorage.go
@@ -194,7 +194,7 @@ var resultPool sync.Pool
 //
 // rss becomes unusable after the call to RunParallel.
 func (rss *Results) RunParallel(qt *querytracer.Tracer, f func(rs *Result, workerID uint) error) error {
-	qt = qt.NewChild()
+	qt = qt.NewChild("parallel process of fetched data")
 	defer rss.mustClose()
 
 	// Spin up local workers.
@@ -256,7 +256,7 @@ func (rss *Results) RunParallel(qt *querytracer.Tracer, f func(rs *Result, worke
 		close(workCh)
 	}
 	workChsWG.Wait()
-	qt.Donef("parallel process of fetched data: series=%d, samples=%d", seriesProcessedTotal, rowsProcessedTotal)
+	qt.Donef("series=%d, samples=%d", seriesProcessedTotal, rowsProcessedTotal)
 
 	return firstErr
 }
@@ -598,8 +598,8 @@ func (sbh *sortBlocksHeap) Pop() interface{} {
 
 // DeleteSeries deletes time series matching the given tagFilterss.
 func DeleteSeries(qt *querytracer.Tracer, sq *storage.SearchQuery, deadline searchutils.Deadline) (int, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("delete series: %s", sq)
+	qt = qt.NewChild("delete series: %s", sq)
+	defer qt.Done()
 	tr := storage.TimeRange{
 		MinTimestamp: sq.MinTimestamp,
 		MaxTimestamp: sq.MaxTimestamp,
@@ -613,8 +613,8 @@ func DeleteSeries(qt *querytracer.Tracer, sq *storage.SearchQuery, deadline sear
 
 // GetLabelsOnTimeRange returns labels for the given tr until the given deadline.
 func GetLabelsOnTimeRange(qt *querytracer.Tracer, tr storage.TimeRange, deadline searchutils.Deadline) ([]string, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get labels on timeRange=%s", &tr)
+	qt = qt.NewChild("get labels on timeRange=%s", &tr)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -637,8 +637,8 @@ func GetLabelsOnTimeRange(qt *querytracer.Tracer, tr storage.TimeRange, deadline
 
 // GetGraphiteTags returns Graphite tags until the given deadline.
 func GetGraphiteTags(qt *querytracer.Tracer, filter string, limit int, deadline searchutils.Deadline) ([]string, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get graphite tags: filter=%s, limit=%d", filter, limit)
+	qt = qt.NewChild("get graphite tags: filter=%s, limit=%d", filter, limit)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -684,8 +684,8 @@ func hasString(a []string, s string) bool {
 
 // GetLabels returns labels until the given deadline.
 func GetLabels(qt *querytracer.Tracer, deadline searchutils.Deadline) ([]string, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get labels")
+	qt = qt.NewChild("get labels")
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -709,8 +709,8 @@ func GetLabels(qt *querytracer.Tracer, deadline searchutils.Deadline) ([]string,
 // GetLabelValuesOnTimeRange returns label values for the given labelName on the given tr
 // until the given deadline.
 func GetLabelValuesOnTimeRange(qt *querytracer.Tracer, labelName string, tr storage.TimeRange, deadline searchutils.Deadline) ([]string, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get values for label %s on a timeRange %s", labelName, &tr)
+	qt = qt.NewChild("get values for label %s on a timeRange %s", labelName, &tr)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -731,8 +731,8 @@ func GetLabelValuesOnTimeRange(qt *querytracer.Tracer, labelName string, tr stor
 
 // GetGraphiteTagValues returns tag values for the given tagName until the given deadline.
 func GetGraphiteTagValues(qt *querytracer.Tracer, tagName, filter string, limit int, deadline searchutils.Deadline) ([]string, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get graphite tag values for tagName=%s, filter=%s, limit=%d", tagName, filter, limit)
+	qt = qt.NewChild("get graphite tag values for tagName=%s, filter=%s, limit=%d", tagName, filter, limit)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -758,8 +758,8 @@ func GetGraphiteTagValues(qt *querytracer.Tracer, tagName, filter string, limit
 // GetLabelValues returns label values for the given labelName
 // until the given deadline.
 func GetLabelValues(qt *querytracer.Tracer, labelName string, deadline searchutils.Deadline) ([]string, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get values for label %s", labelName)
+	qt = qt.NewChild("get values for label %s", labelName)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -782,8 +782,8 @@ func GetLabelValues(qt *querytracer.Tracer, labelName string, deadline searchuti
 //
 // It can be used for implementing https://graphite-api.readthedocs.io/en/latest/api.html#metrics-find
 func GetTagValueSuffixes(qt *querytracer.Tracer, tr storage.TimeRange, tagKey, tagValuePrefix string, delimiter byte, deadline searchutils.Deadline) ([]string, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get tag value suffixes for tagKey=%s, tagValuePrefix=%s, timeRange=%s", tagKey, tagValuePrefix, &tr)
+	qt = qt.NewChild("get tag value suffixes for tagKey=%s, tagValuePrefix=%s, timeRange=%s", tagKey, tagValuePrefix, &tr)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -802,8 +802,8 @@ func GetTagValueSuffixes(qt *querytracer.Tracer, tr storage.TimeRange, tagKey, t
 
 // GetLabelEntries returns all the label entries until the given deadline.
 func GetLabelEntries(qt *querytracer.Tracer, deadline searchutils.Deadline) ([]storage.TagEntry, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get label entries")
+	qt = qt.NewChild("get label entries")
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -836,8 +836,8 @@ func GetLabelEntries(qt *querytracer.Tracer, deadline searchutils.Deadline) ([]s
 
 // GetTSDBStatusForDate returns tsdb status according to https://prometheus.io/docs/prometheus/latest/querying/api/#tsdb-stats
 func GetTSDBStatusForDate(qt *querytracer.Tracer, deadline searchutils.Deadline, date uint64, topN, maxMetrics int) (*storage.TSDBStatus, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get tsdb stats for date=%d, topN=%d", date, topN)
+	qt = qt.NewChild("get tsdb stats for date=%d, topN=%d", date, topN)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -852,8 +852,8 @@ func GetTSDBStatusForDate(qt *querytracer.Tracer, deadline searchutils.Deadline,
 //
 // It accepts aribtrary filters on time series in sq.
 func GetTSDBStatusWithFilters(qt *querytracer.Tracer, deadline searchutils.Deadline, sq *storage.SearchQuery, topN int) (*storage.TSDBStatus, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get tsdb stats: %s, topN=%d", sq, topN)
+	qt = qt.NewChild("get tsdb stats: %s, topN=%d", sq, topN)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -875,8 +875,8 @@ func GetTSDBStatusWithFilters(qt *querytracer.Tracer, deadline searchutils.Deadl
 
 // GetSeriesCount returns the number of unique series.
 func GetSeriesCount(qt *querytracer.Tracer, deadline searchutils.Deadline) (uint64, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("get series count")
+	qt = qt.NewChild("get series count")
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return 0, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
@@ -909,8 +909,8 @@ var ssPool sync.Pool
 // It is the responsibility of f to call b.UnmarshalData before reading timestamps and values from the block.
 // It is the responsibility of f to filter blocks according to the given tr.
 func ExportBlocks(qt *querytracer.Tracer, sq *storage.SearchQuery, deadline searchutils.Deadline, f func(mn *storage.MetricName, b *storage.Block, tr storage.TimeRange) error) error {
-	qt = qt.NewChild()
-	defer qt.Donef("export blocks: %s", sq)
+	qt = qt.NewChild("export blocks: %s", sq)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return fmt.Errorf("timeout exceeded before starting data export: %s", deadline.String())
 	}
@@ -1021,8 +1021,8 @@ var exportWorkPool = &sync.Pool{
 
 // SearchMetricNames returns all the metric names matching sq until the given deadline.
 func SearchMetricNames(qt *querytracer.Tracer, sq *storage.SearchQuery, deadline searchutils.Deadline) ([]storage.MetricName, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("fetch metric names: %s", sq)
+	qt = qt.NewChild("fetch metric names: %s", sq)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting to search metric names: %s", deadline.String())
 	}
@@ -1051,8 +1051,8 @@ func SearchMetricNames(qt *querytracer.Tracer, sq *storage.SearchQuery, deadline
 //
 // Results.RunParallel or Results.Cancel must be called on the returned Results.
 func ProcessSearchQuery(qt *querytracer.Tracer, sq *storage.SearchQuery, fetchData bool, deadline searchutils.Deadline) (*Results, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("fetch matching series: %s, fetchData=%v", sq, fetchData)
+	qt = qt.NewChild("fetch matching series: %s, fetchData=%v", sq, fetchData)
+	defer qt.Done()
 	if deadline.Exceeded() {
 		return nil, fmt.Errorf("timeout exceeded before starting the query processing: %s", deadline.String())
 	}
diff --git a/app/vmselect/prometheus/label_values_response.qtpl b/app/vmselect/prometheus/label_values_response.qtpl
index 24bfbb72b..29d539dcf 100644
--- a/app/vmselect/prometheus/label_values_response.qtpl
+++ b/app/vmselect/prometheus/label_values_response.qtpl
@@ -6,7 +6,7 @@
 
 LabelValuesResponse generates response for /api/v1/label/<labelName>/values .
 See https://prometheus.io/docs/prometheus/latest/querying/api/#querying-label-values
-{% func LabelValuesResponse(labelValues []string, qt *querytracer.Tracer, qtDone func()) %}
+{% func LabelValuesResponse(labelValues []string, qt *querytracer.Tracer) %}
 {
 	"status":"success",
 	"data":[
@@ -17,7 +17,7 @@ See https://prometheus.io/docs/prometheus/latest/querying/api/#querying-label-va
 	]
 	{% code
 		qt.Printf("generate response for %d label values", len(labelValues))
-		qtDone()
+		qt.Done()
 	%}
 	{%= dumpQueryTrace(qt) %}
 }
diff --git a/app/vmselect/prometheus/label_values_response.qtpl.go b/app/vmselect/prometheus/label_values_response.qtpl.go
index b8757ce16..aca097828 100644
--- a/app/vmselect/prometheus/label_values_response.qtpl.go
+++ b/app/vmselect/prometheus/label_values_response.qtpl.go
@@ -25,7 +25,7 @@ var (
 )
 
 //line app/vmselect/prometheus/label_values_response.qtpl:9
-func StreamLabelValuesResponse(qw422016 *qt422016.Writer, labelValues []string, qt *querytracer.Tracer, qtDone func()) {
+func StreamLabelValuesResponse(qw422016 *qt422016.Writer, labelValues []string, qt *querytracer.Tracer) {
 //line app/vmselect/prometheus/label_values_response.qtpl:9
 	qw422016.N().S(`{"status":"success","data":[`)
 //line app/vmselect/prometheus/label_values_response.qtpl:13
@@ -44,7 +44,7 @@ func StreamLabelValuesResponse(qw422016 *qt422016.Writer, labelValues []string,
 	qw422016.N().S(`]`)
 //line app/vmselect/prometheus/label_values_response.qtpl:19
 	qt.Printf("generate response for %d label values", len(labelValues))
-	qtDone()
+	qt.Done()
 
 //line app/vmselect/prometheus/label_values_response.qtpl:22
 	streamdumpQueryTrace(qw422016, qt)
@@ -54,22 +54,22 @@ func StreamLabelValuesResponse(qw422016 *qt422016.Writer, labelValues []string,
 }
 
 //line app/vmselect/prometheus/label_values_response.qtpl:24
-func WriteLabelValuesResponse(qq422016 qtio422016.Writer, labelValues []string, qt *querytracer.Tracer, qtDone func()) {
+func WriteLabelValuesResponse(qq422016 qtio422016.Writer, labelValues []string, qt *querytracer.Tracer) {
 //line app/vmselect/prometheus/label_values_response.qtpl:24
 	qw422016 := qt422016.AcquireWriter(qq422016)
 //line app/vmselect/prometheus/label_values_response.qtpl:24
-	StreamLabelValuesResponse(qw422016, labelValues, qt, qtDone)
+	StreamLabelValuesResponse(qw422016, labelValues, qt)
 //line app/vmselect/prometheus/label_values_response.qtpl:24
 	qt422016.ReleaseWriter(qw422016)
 //line app/vmselect/prometheus/label_values_response.qtpl:24
 }
 
 //line app/vmselect/prometheus/label_values_response.qtpl:24
-func LabelValuesResponse(labelValues []string, qt *querytracer.Tracer, qtDone func()) string {
+func LabelValuesResponse(labelValues []string, qt *querytracer.Tracer) string {
 //line app/vmselect/prometheus/label_values_response.qtpl:24
 	qb422016 := qt422016.AcquireByteBuffer()
 //line app/vmselect/prometheus/label_values_response.qtpl:24
-	WriteLabelValuesResponse(qb422016, labelValues, qt, qtDone)
+	WriteLabelValuesResponse(qb422016, labelValues, qt)
 //line app/vmselect/prometheus/label_values_response.qtpl:24
 	qs422016 := string(qb422016.B)
 //line app/vmselect/prometheus/label_values_response.qtpl:24
diff --git a/app/vmselect/prometheus/labels_response.qtpl b/app/vmselect/prometheus/labels_response.qtpl
index 9db265c3b..4e5ab6279 100644
--- a/app/vmselect/prometheus/labels_response.qtpl
+++ b/app/vmselect/prometheus/labels_response.qtpl
@@ -6,7 +6,7 @@
 
 LabelsResponse generates response for /api/v1/labels .
 See https://prometheus.io/docs/prometheus/latest/querying/api/#getting-label-names
-{% func LabelsResponse(labels []string, qt *querytracer.Tracer, qtDone func()) %}
+{% func LabelsResponse(labels []string, qt *querytracer.Tracer) %}
 {
 	"status":"success",
 	"data":[
@@ -17,7 +17,7 @@ See https://prometheus.io/docs/prometheus/latest/querying/api/#getting-label-nam
 	]
 	{% code
 		qt.Printf("generate response for %d labels", len(labels))
-		qtDone()
+		qt.Done()
 	%}
 	{%= dumpQueryTrace(qt) %}
 }
diff --git a/app/vmselect/prometheus/labels_response.qtpl.go b/app/vmselect/prometheus/labels_response.qtpl.go
index d7540d5d5..8c6853bb3 100644
--- a/app/vmselect/prometheus/labels_response.qtpl.go
+++ b/app/vmselect/prometheus/labels_response.qtpl.go
@@ -25,7 +25,7 @@ var (
 )
 
 //line app/vmselect/prometheus/labels_response.qtpl:9
-func StreamLabelsResponse(qw422016 *qt422016.Writer, labels []string, qt *querytracer.Tracer, qtDone func()) {
+func StreamLabelsResponse(qw422016 *qt422016.Writer, labels []string, qt *querytracer.Tracer) {
 //line app/vmselect/prometheus/labels_response.qtpl:9
 	qw422016.N().S(`{"status":"success","data":[`)
 //line app/vmselect/prometheus/labels_response.qtpl:13
@@ -44,7 +44,7 @@ func StreamLabelsResponse(qw422016 *qt422016.Writer, labels []string, qt *queryt
 	qw422016.N().S(`]`)
 //line app/vmselect/prometheus/labels_response.qtpl:19
 	qt.Printf("generate response for %d labels", len(labels))
-	qtDone()
+	qt.Done()
 
 //line app/vmselect/prometheus/labels_response.qtpl:22
 	streamdumpQueryTrace(qw422016, qt)
@@ -54,22 +54,22 @@ func StreamLabelsResponse(qw422016 *qt422016.Writer, labels []string, qt *queryt
 }
 
 //line app/vmselect/prometheus/labels_response.qtpl:24
-func WriteLabelsResponse(qq422016 qtio422016.Writer, labels []string, qt *querytracer.Tracer, qtDone func()) {
+func WriteLabelsResponse(qq422016 qtio422016.Writer, labels []string, qt *querytracer.Tracer) {
 //line app/vmselect/prometheus/labels_response.qtpl:24
 	qw422016 := qt422016.AcquireWriter(qq422016)
 //line app/vmselect/prometheus/labels_response.qtpl:24
-	StreamLabelsResponse(qw422016, labels, qt, qtDone)
+	StreamLabelsResponse(qw422016, labels, qt)
 //line app/vmselect/prometheus/labels_response.qtpl:24
 	qt422016.ReleaseWriter(qw422016)
 //line app/vmselect/prometheus/labels_response.qtpl:24
 }
 
 //line app/vmselect/prometheus/labels_response.qtpl:24
-func LabelsResponse(labels []string, qt *querytracer.Tracer, qtDone func()) string {
+func LabelsResponse(labels []string, qt *querytracer.Tracer) string {
 //line app/vmselect/prometheus/labels_response.qtpl:24
 	qb422016 := qt422016.AcquireByteBuffer()
 //line app/vmselect/prometheus/labels_response.qtpl:24
-	WriteLabelsResponse(qb422016, labels, qt, qtDone)
+	WriteLabelsResponse(qb422016, labels, qt)
 //line app/vmselect/prometheus/labels_response.qtpl:24
 	qs422016 := string(qb422016.B)
 //line app/vmselect/prometheus/labels_response.qtpl:24
diff --git a/app/vmselect/prometheus/prometheus.go b/app/vmselect/prometheus/prometheus.go
index ecd4341eb..560599f05 100644
--- a/app/vmselect/prometheus/prometheus.go
+++ b/app/vmselect/prometheus/prometheus.go
@@ -361,7 +361,7 @@ func exportHandler(qt *querytracer.Tracer, w http.ResponseWriter, ep *exportPara
 		if err != nil {
 			return fmt.Errorf("cannot fetch data for %q: %w", sq, err)
 		}
-		qtChild := qt.NewChild()
+		qtChild := qt.NewChild("background export format=%s", format)
 		go func() {
 			err := rss.RunParallel(qtChild, func(rs *netstorage.Result, workerID uint) error {
 				if err := bw.Error(); err != nil {
@@ -376,12 +376,12 @@ func exportHandler(qt *querytracer.Tracer, w http.ResponseWriter, ep *exportPara
 				exportBlockPool.Put(xb)
 				return nil
 			})
-			qtChild.Donef("background export format=%s", format)
+			qtChild.Done()
 			close(resultsCh)
 			doneCh <- err
 		}()
 	} else {
-		qtChild := qt.NewChild()
+		qtChild := qt.NewChild("background export format=%s", format)
 		go func() {
 			err := netstorage.ExportBlocks(qtChild, sq, ep.deadline, func(mn *storage.MetricName, b *storage.Block, tr storage.TimeRange) error {
 				if err := bw.Error(); err != nil {
@@ -400,7 +400,7 @@ func exportHandler(qt *querytracer.Tracer, w http.ResponseWriter, ep *exportPara
 				exportBlockPool.Put(xb)
 				return nil
 			})
-			qtChild.Donef("background export format=%s", format)
+			qtChild.Done()
 			close(resultsCh)
 			doneCh <- err
 		}()
@@ -535,10 +535,7 @@ func LabelValuesHandler(qt *querytracer.Tracer, startTime time.Time, labelName s
 	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
-	qtDone := func() {
-		qt.Donef("/api/v1/labels")
-	}
-	WriteLabelValuesResponse(bw, labelValues, qt, qtDone)
+	WriteLabelValuesResponse(bw, labelValues, qt)
 	if err := bw.Flush(); err != nil {
 		return fmt.Errorf("canot flush label values to remote client: %w", err)
 	}
@@ -791,10 +788,7 @@ func LabelsHandler(qt *querytracer.Tracer, startTime time.Time, w http.ResponseW
 	w.Header().Set("Content-Type", "application/json")
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
-	qtDone := func() {
-		qt.Donef("/api/v1/labels")
-	}
-	WriteLabelsResponse(bw, labels, qt, qtDone)
+	WriteLabelsResponse(bw, labels, qt)
 	if err := bw.Flush(); err != nil {
 		return fmt.Errorf("cannot send labels response to remote client: %w", err)
 	}
@@ -914,7 +908,7 @@ func SeriesHandler(qt *querytracer.Tracer, startTime time.Time, w http.ResponseW
 	}
 	sq := storage.NewSearchQuery(start, end, tagFilterss, *maxSeriesLimit)
 	qtDone := func() {
-		qt.Donef("/api/v1/series: start=%d, end=%d", start, end)
+		qt.Donef("start=%d, end=%d", start, end)
 	}
 	if end-start > 24*3600*1000 {
 		// It is cheaper to call SearchMetricNames on time ranges exceeding a day.
@@ -1101,7 +1095,7 @@ func QueryHandler(qt *querytracer.Tracer, startTime time.Time, w http.ResponseWr
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	qtDone := func() {
-		qt.Donef("/api/v1/query: query=%s, time=%d: series=%d", query, start, len(result))
+		qt.Donef("query=%s, time=%d: series=%d", query, start, len(result))
 	}
 	WriteQueryResponse(bw, result, qt, qtDone)
 	if err := bw.Flush(); err != nil {
@@ -1199,7 +1193,7 @@ func queryRangeHandler(qt *querytracer.Tracer, startTime time.Time, w http.Respo
 	bw := bufferedwriter.Get(w)
 	defer bufferedwriter.Put(bw)
 	qtDone := func() {
-		qt.Donef("/api/v1/query_range: start=%d, end=%d, step=%d, query=%q: series=%d", start, end, step, query, len(result))
+		qt.Donef("start=%d, end=%d, step=%d, query=%q: series=%d", start, end, step, query, len(result))
 	}
 	WriteQueryRangeResponse(bw, result, qt, qtDone)
 	if err := bw.Flush(); err != nil {
diff --git a/app/vmselect/promql/eval.go b/app/vmselect/promql/eval.go
index 3a1e33216..a0a26deaa 100644
--- a/app/vmselect/promql/eval.go
+++ b/app/vmselect/promql/eval.go
@@ -193,22 +193,23 @@ func getTimestamps(start, end, step int64) []int64 {
 }
 
 func evalExpr(qt *querytracer.Tracer, ec *EvalConfig, e metricsql.Expr) ([]*timeseries, error) {
-	qt = qt.NewChild()
+	if qt.Enabled() {
+		query := e.AppendString(nil)
+		mayCache := ec.mayCache()
+		qt = qt.NewChild("eval: query=%s, timeRange=[%d..%d], step=%d, mayCache=%v", query, ec.Start, ec.End, ec.Step, mayCache)
+	}
 	rv, err := evalExprInternal(qt, ec, e)
 	if err != nil {
 		return nil, err
 	}
 	if qt.Enabled() {
-		query := e.AppendString(nil)
 		seriesCount := len(rv)
 		pointsPerSeries := 0
 		if len(rv) > 0 {
 			pointsPerSeries = len(rv[0].Timestamps)
 		}
 		pointsCount := seriesCount * pointsPerSeries
-		mayCache := ec.mayCache()
-		qt.Donef("eval: query=%s, timeRange=[%d..%d], step=%d, mayCache=%v: series=%d, points=%d, pointsPerSeries=%d",
-			query, ec.Start, ec.End, ec.Step, mayCache, seriesCount, pointsCount, pointsPerSeries)
+		qt.Donef("series=%d, points=%d, pointsPerSeries=%d", seriesCount, pointsCount, pointsPerSeries)
 	}
 	return rv, nil
 }
@@ -234,9 +235,9 @@ func evalExprInternal(qt *querytracer.Tracer, ec *EvalConfig, e metricsql.Expr)
 	if fe, ok := e.(*metricsql.FuncExpr); ok {
 		nrf := getRollupFunc(fe.Name)
 		if nrf == nil {
-			qtChild := qt.NewChild()
+			qtChild := qt.NewChild("transform %s()", fe.Name)
 			rv, err := evalTransformFunc(qtChild, ec, fe)
-			qtChild.Donef("transform %s(): series=%d", fe.Name, len(rv))
+			qtChild.Donef("series=%d", len(rv))
 			return rv, err
 		}
 		args, re, err := evalRollupFuncArgs(qt, ec, fe)
@@ -254,15 +255,15 @@ func evalExprInternal(qt *querytracer.Tracer, ec *EvalConfig, e metricsql.Expr)
 		return rv, nil
 	}
 	if ae, ok := e.(*metricsql.AggrFuncExpr); ok {
-		qtChild := qt.NewChild()
+		qtChild := qt.NewChild("aggregate %s()", ae.Name)
 		rv, err := evalAggrFunc(qtChild, ec, ae)
-		qtChild.Donef("aggregate %s(): series=%d", ae.Name, len(rv))
+		qtChild.Donef("series=%d", len(rv))
 		return rv, err
 	}
 	if be, ok := e.(*metricsql.BinaryOpExpr); ok {
-		qtChild := qt.NewChild()
+		qtChild := qt.NewChild("binary op %q", be.Op)
 		rv, err := evalBinaryOp(qtChild, ec, be)
-		qtChild.Donef("binary op %q: series=%d", be.Op, len(rv))
+		qtChild.Donef("series=%d", len(rv))
 		return rv, err
 	}
 	if ne, ok := e.(*metricsql.NumberExpr); ok {
@@ -724,8 +725,8 @@ func aggregateAbsentOverTime(ec *EvalConfig, expr metricsql.Expr, tss []*timeser
 
 func evalRollupFuncWithSubquery(qt *querytracer.Tracer, ec *EvalConfig, funcName string, rf rollupFunc, expr metricsql.Expr, re *metricsql.RollupExpr) ([]*timeseries, error) {
 	// TODO: determine whether to use rollupResultCacheV here.
-	qt = qt.NewChild()
-	defer qt.Donef("subquery")
+	qt = qt.NewChild("subquery")
+	defer qt.Done()
 	step := re.Step.Duration(ec.Step)
 	if step == 0 {
 		step = ec.Step
@@ -855,9 +856,9 @@ func evalRollupFuncWithMetricExpr(qt *querytracer.Tracer, ec *EvalConfig, funcNa
 	expr metricsql.Expr, me *metricsql.MetricExpr, iafc *incrementalAggrFuncContext, windowExpr *metricsql.DurationExpr) ([]*timeseries, error) {
 	var rollupMemorySize int64
 	window := windowExpr.Duration(ec.Step)
-	qt = qt.NewChild()
+	qt = qt.NewChild("rollup %s(): timeRange=[%d..%d], step=%d, window=%d", funcName, ec.Start, ec.End, ec.Step, window)
 	defer func() {
-		qt.Donef("rollup %s(): timeRange=[%d..%d], step=%d, window=%d, neededMemoryBytes=%d", funcName, ec.Start, ec.End, ec.Step, window, rollupMemorySize)
+		qt.Donef("neededMemoryBytes=%d", rollupMemorySize)
 	}()
 	if me.IsEmpty() {
 		return evalNumber(ec, nan), nil
@@ -972,8 +973,8 @@ func getRollupMemoryLimiter() *memoryLimiter {
 func evalRollupWithIncrementalAggregate(qt *querytracer.Tracer, funcName string, keepMetricNames bool,
 	iafc *incrementalAggrFuncContext, rss *netstorage.Results, rcs []*rollupConfig,
 	preFunc func(values []float64, timestamps []int64), sharedTimestamps []int64) ([]*timeseries, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("rollup %s() with incremental aggregation %s() over %d series", funcName, iafc.ae.Name, rss.Len())
+	qt = qt.NewChild("rollup %s() with incremental aggregation %s() over %d series", funcName, iafc.ae.Name, rss.Len())
+	defer qt.Done()
 	err := rss.RunParallel(qt, func(rs *netstorage.Result, workerID uint) error {
 		rs.Values, rs.Timestamps = dropStaleNaNs(funcName, rs.Values, rs.Timestamps)
 		preFunc(rs.Values, rs.Timestamps)
@@ -1007,8 +1008,8 @@ func evalRollupWithIncrementalAggregate(qt *querytracer.Tracer, funcName string,
 
 func evalRollupNoIncrementalAggregate(qt *querytracer.Tracer, funcName string, keepMetricNames bool, rss *netstorage.Results, rcs []*rollupConfig,
 	preFunc func(values []float64, timestamps []int64), sharedTimestamps []int64) ([]*timeseries, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("rollup %s() over %d series", funcName, rss.Len())
+	qt = qt.NewChild("rollup %s() over %d series", funcName, rss.Len())
+	defer qt.Done()
 	tss := make([]*timeseries, 0, rss.Len()*len(rcs))
 	var tssLock sync.Mutex
 	err := rss.RunParallel(qt, func(rs *netstorage.Result, workerID uint) error {
diff --git a/app/vmselect/promql/rollup_result_cache.go b/app/vmselect/promql/rollup_result_cache.go
index b5449afa4..d005402e3 100644
--- a/app/vmselect/promql/rollup_result_cache.go
+++ b/app/vmselect/promql/rollup_result_cache.go
@@ -200,10 +200,10 @@ func ResetRollupResultCache() {
 }
 
 func (rrc *rollupResultCache) Get(qt *querytracer.Tracer, ec *EvalConfig, expr metricsql.Expr, window int64) (tss []*timeseries, newStart int64) {
-	qt = qt.NewChild()
 	if qt.Enabled() {
 		query := expr.AppendString(nil)
-		defer qt.Donef("rollup cache get: query=%s, timeRange=[%d..%d], step=%d, window=%d", query, ec.Start, ec.End, ec.Step, window)
+		qt = qt.NewChild("rollup cache get: query=%s, timeRange=[%d..%d], step=%d, window=%d", query, ec.Start, ec.End, ec.Step, window)
+		defer qt.Done()
 	}
 	if !ec.mayCache() {
 		qt.Printf("do not fetch series from cache, since it is disabled in the current context")
@@ -296,10 +296,10 @@ func (rrc *rollupResultCache) Get(qt *querytracer.Tracer, ec *EvalConfig, expr m
 var resultBufPool bytesutil.ByteBufferPool
 
 func (rrc *rollupResultCache) Put(qt *querytracer.Tracer, ec *EvalConfig, expr metricsql.Expr, window int64, tss []*timeseries) {
-	qt = qt.NewChild()
 	if qt.Enabled() {
 		query := expr.AppendString(nil)
-		defer qt.Donef("rollup cache put: query=%s, timeRange=[%d..%d], step=%d, window=%d, series=%d", query, ec.Start, ec.End, ec.Step, window, len(tss))
+		qt = qt.NewChild("rollup cache put: query=%s, timeRange=[%d..%d], step=%d, window=%d, series=%d", query, ec.Start, ec.End, ec.Step, window, len(tss))
+		defer qt.Done()
 	}
 	if len(tss) == 0 || !ec.mayCache() {
 		qt.Printf("do not store series to cache, since it is disabled in the current context")
diff --git a/docs/README.md b/docs/README.md
index d126a4861..084367ee3 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -1425,7 +1425,7 @@ In this case VictoriaMetrics puts query trace into `trace` field in the output J
 For example, the following command:
 
 ```bash
-curl http://localhost:8428/api/v1/query_range -d 'query=2*rand()' -d 'start=-1h' -d 'step=1m' -d 'trace=1' | jq -r '.trace'
+curl http://localhost:8428/api/v1/query_range -d 'query=2*rand()' -d 'start=-1h' -d 'step=1m' -d 'trace=1' | jq '.trace'
 ```
 
 would return the following trace:
diff --git a/docs/Single-server-VictoriaMetrics.md b/docs/Single-server-VictoriaMetrics.md
index e47210099..c6b8e65c3 100644
--- a/docs/Single-server-VictoriaMetrics.md
+++ b/docs/Single-server-VictoriaMetrics.md
@@ -1429,7 +1429,7 @@ In this case VictoriaMetrics puts query trace into `trace` field in the output J
 For example, the following command:
 
 ```bash
-curl http://localhost:8428/api/v1/query_range -d 'query=2*rand()' -d 'start=-1h' -d 'step=1m' -d 'trace=1' | jq -r '.trace'
+curl http://localhost:8428/api/v1/query_range -d 'query=2*rand()' -d 'start=-1h' -d 'step=1m' -d 'trace=1' | jq '.trace'
 ```
 
 would return the following trace:
diff --git a/lib/querytracer/tracer.go b/lib/querytracer/tracer.go
index 0e22234c3..a6467973a 100644
--- a/lib/querytracer/tracer.go
+++ b/lib/querytracer/tracer.go
@@ -15,16 +15,16 @@ var denyQueryTracing = flag.Bool("denyQueryTracing", false, "Whether to disable
 // Tracer represents query tracer.
 //
 // It must be created via New call.
-// Each created tracer must be finalized via Donef call.
+// Each created tracer must be finalized via Done or Donef call.
 //
 // Tracer may contain sub-tracers (branches) in order to build tree-like execution order.
 // Call Tracer.NewChild func for adding sub-tracer.
 type Tracer struct {
 	// startTime is the time when Tracer was created
 	startTime time.Time
-	// doneTime is the time when Donef was called
+	// doneTime is the time when Done or Donef was called
 	doneTime time.Time
-	// message is the message generated by Printf or Donef call.
+	// message is the message generated by NewChild, Printf or Donef call.
 	message string
 	// children is a list of children Tracer objects
 	children []*Tracer
@@ -33,16 +33,17 @@ type Tracer struct {
 	span *span
 }
 
-// New creates a new instance of the tracer.
+// New creates a new instance of the tracer with the given fmt.Sprintf(format, args...) message.
 //
 // If enabled isn't set, then all function calls to the returned object will be no-op.
 //
-// Donef must be called when the tracer should be finished.
-func New(enabled bool) *Tracer {
+// Done or Donef must be called when the tracer should be finished.
+func New(enabled bool, format string, args ...interface{}) *Tracer {
 	if *denyQueryTracing || !enabled {
 		return nil
 	}
 	return &Tracer{
+		message:   fmt.Sprintf(format, args...),
 		startTime: time.Now(),
 	}
 }
@@ -52,26 +53,43 @@ func (t *Tracer) Enabled() bool {
 	return t != nil
 }
 
-// NewChild adds a new child Tracer to t.
+// NewChild adds a new child Tracer to t with the given fmt.Sprintf(format, args...) message.
+//
+// The returned child must be closed via Done or Donef calls.
 //
 // NewChild cannot be called from concurrent goroutines.
 // Create children tracers from a single goroutine and then pass them
 // to concurrent goroutines.
-func (t *Tracer) NewChild() *Tracer {
+func (t *Tracer) NewChild(format string, args ...interface{}) *Tracer {
 	if t == nil {
 		return nil
 	}
-	if t.message != "" {
+	if !t.doneTime.IsZero() {
 		panic(fmt.Errorf("BUG: NewChild() cannot be called after Donef(%q) call", t.message))
 	}
 	child := &Tracer{
+		message:   fmt.Sprintf(format, args...),
 		startTime: time.Now(),
 	}
 	t.children = append(t.children, child)
 	return child
 }
 
-// Donef finishes t.
+// Done finishes t.
+//
+// Done cannot be called multiple times.
+// Other Tracer functions cannot be called after Done call.
+func (t *Tracer) Done() {
+	if t == nil {
+		return
+	}
+	if !t.doneTime.IsZero() {
+		panic(fmt.Errorf("BUG: Donef(%q) already called", t.message))
+	}
+	t.doneTime = time.Now()
+}
+
+// Donef appends the given fmt.Sprintf(format, args..) message to t and finished it.
 //
 // Donef cannot be called multiple times.
 // Other Tracer functions cannot be called after Donef call.
@@ -79,21 +97,21 @@ func (t *Tracer) Donef(format string, args ...interface{}) {
 	if t == nil {
 		return
 	}
-	if t.message != "" {
-		panic(fmt.Errorf("BUG: Donef() already called with message %q", t.message))
+	if !t.doneTime.IsZero() {
+		panic(fmt.Errorf("BUG: Donef(%q) already called", t.message))
 	}
-	t.message = fmt.Sprintf(format, args...)
+	t.message += ": " + fmt.Sprintf(format, args...)
 	t.doneTime = time.Now()
 }
 
-// Printf adds new message to t.
+// Printf adds new fmt.Sprintf(format, args...) message to t.
 //
 // Printf cannot be called from concurrent goroutines.
 func (t *Tracer) Printf(format string, args ...interface{}) {
 	if t == nil {
 		return
 	}
-	if t.message != "" {
+	if !t.doneTime.IsZero() {
 		panic(fmt.Errorf("BUG: Printf() cannot be called after Done(%q) call", t.message))
 	}
 	now := time.Now()
@@ -177,8 +195,8 @@ func (t *Tracer) toSpanInternal(prevTime time.Time) (*span, time.Time) {
 	// tracer with children
 	msg := t.message
 	doneTime := t.doneTime
-	if msg == "" {
-		msg = "missing Tracer.Donef() call"
+	if doneTime.IsZero() {
+		msg += ": missing Tracer.Done() call"
 		doneTime = t.getLastChildDoneTime(t.startTime)
 	}
 	d := doneTime.Sub(t.startTime)
diff --git a/lib/querytracer/tracer_test.go b/lib/querytracer/tracer_test.go
index 8e8660aa5..fa278d2b7 100644
--- a/lib/querytracer/tracer_test.go
+++ b/lib/querytracer/tracer_test.go
@@ -6,21 +6,21 @@ import (
 )
 
 func TestTracerDisabled(t *testing.T) {
-	qt := New(false)
+	qt := New(false, "test")
 	if qt.Enabled() {
 		t.Fatalf("query tracer must be disabled")
 	}
-	qtChild := qt.NewChild()
+	qtChild := qt.NewChild("child done %d", 456)
 	if qtChild.Enabled() {
 		t.Fatalf("query tracer must be disabled")
 	}
 	qtChild.Printf("foo %d", 123)
-	qtChild.Donef("child done %d", 456)
+	qtChild.Done()
 	qt.Printf("parent %d", 789)
 	if err := qt.AddJSON([]byte("foobar")); err != nil {
 		t.Fatalf("unexpected error in AddJSON: %s", err)
 	}
-	qt.Donef("test")
+	qt.Done()
 	s := qt.String()
 	if s != "" {
 		t.Fatalf("unexpected trace; got %s; want empty", s)
@@ -32,20 +32,20 @@ func TestTracerDisabled(t *testing.T) {
 }
 
 func TestTracerEnabled(t *testing.T) {
-	qt := New(true)
+	qt := New(true, "test")
 	if !qt.Enabled() {
 		t.Fatalf("query tracer must be enabled")
 	}
-	qtChild := qt.NewChild()
+	qtChild := qt.NewChild("child done %d", 456)
 	if !qtChild.Enabled() {
 		t.Fatalf("child query tracer must be enabled")
 	}
 	qtChild.Printf("foo %d", 123)
-	qtChild.Donef("child done %d", 456)
+	qtChild.Done()
 	qt.Printf("parent %d", 789)
-	qt.Donef("test")
+	qt.Donef("foo %d", 33)
 	s := qt.String()
-	sExpected := `- 0ms: test
+	sExpected := `- 0ms: test: foo 33
 | - 0ms: child done 456
 | | - 0ms: foo 123
 | - 0ms: parent 789
@@ -56,9 +56,9 @@ func TestTracerEnabled(t *testing.T) {
 }
 
 func TestTracerMultiline(t *testing.T) {
-	qt := New(true)
+	qt := New(true, "line1\nline2")
 	qt.Printf("line3\nline4\n")
-	qt.Donef("line1\nline2")
+	qt.Done()
 	s := qt.String()
 	sExpected := `- 0ms: line1
 | line2
@@ -71,18 +71,18 @@ func TestTracerMultiline(t *testing.T) {
 }
 
 func TestTracerToJSON(t *testing.T) {
-	qt := New(true)
+	qt := New(true, "test")
 	if !qt.Enabled() {
 		t.Fatalf("query tracer must be enabled")
 	}
-	qtChild := qt.NewChild()
+	qtChild := qt.NewChild("child done %d", 456)
 	if !qtChild.Enabled() {
 		t.Fatalf("child query tracer must be enabled")
 	}
 	qtChild.Printf("foo %d", 123)
-	qtChild.Donef("child done %d", 456)
+	qtChild.Done()
 	qt.Printf("parent %d", 789)
-	qt.Donef("test")
+	qt.Done()
 	s := qt.ToJSON()
 	sExpected := `{"duration_msec":0,"message":"test","children":[` +
 		`{"duration_msec":0,"message":"child done 456","children":[` +
@@ -94,11 +94,11 @@ func TestTracerToJSON(t *testing.T) {
 }
 
 func TestTraceAddJSON(t *testing.T) {
-	qtChild := New(true)
+	qtChild := New(true, "child")
 	qtChild.Printf("foo")
-	qtChild.Donef("child")
+	qtChild.Done()
 	jsonTrace := qtChild.ToJSON()
-	qt := New(true)
+	qt := New(true, "parent")
 	qt.Printf("first_line")
 	if err := qt.AddJSON([]byte(jsonTrace)); err != nil {
 		t.Fatalf("unexpected error in AddJSON: %s", err)
@@ -107,7 +107,7 @@ func TestTraceAddJSON(t *testing.T) {
 	if err := qt.AddJSON(nil); err != nil {
 		t.Fatalf("unexpected error in AddJSON(nil): %s", err)
 	}
-	qt.Donef("parent")
+	qt.Done()
 	s := qt.String()
 	sExpected := `- 0ms: parent
 | - 0ms: first_line
@@ -131,15 +131,15 @@ func TestTraceAddJSON(t *testing.T) {
 }
 
 func TestTraceMissingDonef(t *testing.T) {
-	qt := New(true)
+	qt := New(true, "parent")
 	qt.Printf("parent printf")
-	qtChild := qt.NewChild()
+	qtChild := qt.NewChild("child")
 	qtChild.Printf("child printf")
 	qt.Printf("another parent printf")
 	s := qt.String()
-	sExpected := `- 0ms: missing Tracer.Donef() call
+	sExpected := `- 0ms: parent: missing Tracer.Done() call
 | - 0ms: parent printf
-| - 0ms: missing Tracer.Donef() call
+| - 0ms: child: missing Tracer.Done() call
 | | - 0ms: child printf
 | - 0ms: another parent printf
 `
diff --git a/lib/storage/search.go b/lib/storage/search.go
index d74788e21..761b19845 100644
--- a/lib/storage/search.go
+++ b/lib/storage/search.go
@@ -141,8 +141,8 @@ func (s *Search) reset() {
 //
 // Init returns the upper bound on the number of found time series.
 func (s *Search) Init(qt *querytracer.Tracer, storage *Storage, tfss []*TagFilters, tr TimeRange, maxMetrics int, deadline uint64) int {
-	qt = qt.NewChild()
-	defer qt.Donef("init series search: filters=%s, timeRange=%s", tfss, &tr)
+	qt = qt.NewChild("init series search: filters=%s, timeRange=%s", tfss, &tr)
+	defer qt.Done()
 	if s.needClosing {
 		logger.Panicf("BUG: missing MustClose call before the next call to Init")
 	}
diff --git a/lib/storage/storage.go b/lib/storage/storage.go
index 6807efca2..f968d0663 100644
--- a/lib/storage/storage.go
+++ b/lib/storage/storage.go
@@ -1061,8 +1061,8 @@ func nextRetentionDuration(retentionMsecs int64) time.Duration {
 
 // SearchMetricNames returns metric names matching the given tfss on the given tr.
 func (s *Storage) SearchMetricNames(qt *querytracer.Tracer, tfss []*TagFilters, tr TimeRange, maxMetrics int, deadline uint64) ([]MetricName, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("search for matching metric names")
+	qt = qt.NewChild("search for matching metric names")
+	defer qt.Done()
 	tsids, err := s.searchTSIDs(qt, tfss, tr, maxMetrics, deadline)
 	if err != nil {
 		return nil, err
@@ -1104,8 +1104,8 @@ func (s *Storage) SearchMetricNames(qt *querytracer.Tracer, tfss []*TagFilters,
 
 // searchTSIDs returns sorted TSIDs for the given tfss and the given tr.
 func (s *Storage) searchTSIDs(qt *querytracer.Tracer, tfss []*TagFilters, tr TimeRange, maxMetrics int, deadline uint64) ([]TSID, error) {
-	qt = qt.NewChild()
-	defer qt.Donef("search for matching series ids")
+	qt = qt.NewChild("search for matching series ids")
+	defer qt.Done()
 	// Do not cache tfss -> tsids here, since the caching is performed
 	// on idb level.
 
@@ -1154,8 +1154,8 @@ var (
 //
 // This should speed-up further searchMetricNameWithCache calls for metricIDs from tsids.
 func (s *Storage) prefetchMetricNames(qt *querytracer.Tracer, tsids []TSID, deadline uint64) error {
-	qt = qt.NewChild()
-	defer qt.Donef("prefetch metric names for %d series ids", len(tsids))
+	qt = qt.NewChild("prefetch metric names for %d series ids", len(tsids))
+	defer qt.Done()
 	if len(tsids) == 0 {
 		qt.Printf("nothing to prefetch")
 		return nil