Merge pull request #70171 from adityamaru/backport20.2-69538

release-20.2: metric: fix missing mutex handling in metrics registry

pkg/util/metric/registry.go

@@ -139,6 +139,8 @@ func (r *Registry) addMetricValue(
 // WriteMetricsMetadata writes metadata from all tracked metrics to the
 // parameter map.
 func (r *Registry) WriteMetricsMetadata(dest map[string]Metadata) {
+	r.Lock()
+	defer r.Unlock()
 	for _, v := range r.tracked {
 		dest[v.GetName()] = v.GetMetadata()
 	}
@@ -157,6 +159,8 @@ func (r *Registry) Each(f func(name string, val interface{})) {
 
 // MarshalJSON marshals to JSON.
 func (r *Registry) MarshalJSON() ([]byte, error) {
+	r.Lock()
+	defer r.Unlock()
 	m := make(map[string]interface{})
 	for _, metric := range r.tracked {
 		metric.Inspect(func(v interface{}) {

pkg/util/metric/registry_test.go

@@ -16,6 +16,8 @@ import (
 )
 
 func (r *Registry) findMetricByName(name string) Iterable {
+	r.Lock()
+	defer r.Unlock()
 	for _, metric := range r.tracked {
 		if metric.GetName() == name {
 			return metric
@@ -28,8 +30,6 @@ func (r *Registry) findMetricByName(name string) Iterable {
 // Counter with this name is not present (including if a non-Counter Iterable is
 // registered with the name), nil is returned.
 func (r *Registry) getCounter(name string) *Counter {
-	r.Lock()
-	defer r.Unlock()
 	iterable := r.findMetricByName(name)
 	if iterable == nil {
 		return nil
@@ -47,8 +47,6 @@ func (r *Registry) getCounter(name string) *Counter {
 // with this name is not present (including if a non-Gauge Iterable is
 // registered with the name), nil is returned.
 func (r *Registry) getGauge(name string) *Gauge {
-	r.Lock()
-	defer r.Unlock()
 	iterable := r.findMetricByName(name)
 	if iterable == nil {
 		return nil