fix(pruner): unregister callbck from meter on stop

pruner/metrics.go

@@ -17,6 +17,8 @@ type metrics struct {
 
 	lastPruned   metric.Int64ObservableGauge
 	failedPrunes metric.Int64ObservableGauge
+
+	clientReg metric.Registration
 }
 
 func (s *Service) WithMetrics() error {
@@ -44,18 +46,28 @@ func (s *Service) WithMetrics() error {
 		return nil
 	}
 
-	if _, err := meter.RegisterCallback(callback, lastPruned, failedPrunes); err != nil {
+	clientReg, err := meter.RegisterCallback(callback, lastPruned, failedPrunes)
+	if err != nil {
 		return err
 	}
 
 	s.metrics = &metrics{
 		prunedCounter: prunedCounter,
 		lastPruned:    lastPruned,
 		failedPrunes:  failedPrunes,
+		clientReg:     clientReg,
 	}
 	return nil
 }
 
+func (m *metrics) close() error {
+	if m == nil {
+		return nil
+	}
+
+	return m.clientReg.Unregister()
+}
+
 func (m *metrics) observePrune(ctx context.Context, failed bool) {
 	if m == nil {
 		return

pruner/service.go

@@ -84,6 +84,8 @@ func (s *Service) Start(context.Context) error {
 func (s *Service) Stop(ctx context.Context) error {
 	s.cancel()
 
+	s.metrics.close()
+
 	select {
 	case <-s.doneCh:
 		return nil