don't register Producers after shutdown

Author: dashpole

sdk/metric/manual_reader.go

@@ -32,6 +32,7 @@ type manualReader struct {
 	shutdownOnce sync.Once
 
 	mu                sync.Mutex
+	isShutdown        bool
 	externalProducers atomic.Value
 
 	temporalitySelector TemporalitySelector
@@ -67,6 +68,9 @@ func (mr *manualReader) register(p sdkProducer) {
 func (mr *manualReader) RegisterProducer(p Producer) {
 	mr.mu.Lock()
 	defer mr.mu.Unlock()
+	if mr.isShutdown {
+		return
+	}
 	currentProducers := mr.externalProducers.Load().([]Producer)
 	newProducers := []Producer{}
 	newProducers = append(newProducers, currentProducers...)
@@ -97,6 +101,9 @@ func (mr *manualReader) Shutdown(context.Context) error {
 		mr.sdkProducer.Store(produceHolder{
 			produce: shutdownProducer{}.produce,
 		})
+		mr.mu.Lock()
+		defer mr.mu.Unlock()
+		mr.isShutdown = true
 		// release references to Producer(s)
 		mr.externalProducers.Store([]Producer{})
 		err = nil

sdk/metric/periodic_reader.go

@@ -130,6 +130,7 @@ type periodicReader struct {
 	sdkProducer atomic.Value
 
 	mu                sync.Mutex
+	isShutdown        bool
 	externalProducers atomic.Value
 
 	timeout  time.Duration
@@ -182,6 +183,9 @@ func (r *periodicReader) register(p sdkProducer) {
 func (r *periodicReader) RegisterProducer(p Producer) {
 	r.mu.Lock()
 	defer r.mu.Unlock()
+	if r.isShutdown {
+		return
+	}
 	currentProducers := r.externalProducers.Load().([]Producer)
 	newProducers := []Producer{}
 	newProducers = append(newProducers, currentProducers...)
@@ -301,13 +305,16 @@ func (r *periodicReader) Shutdown(ctx context.Context) error {
 			}
 		}
 
-		// release references to Producer(s)
-		r.externalProducers.Store([]Producer{})
-
 		sErr := r.exporter.Shutdown(ctx)
 		if err == nil || err == ErrReaderShutdown {
 			err = sErr
 		}
+
+		r.mu.Lock()
+		defer r.mu.Unlock()
+		r.isShutdown = true
+		// release references to Producer(s)
+		r.externalProducers.Store([]Producer{})
 	})
 	return err
 }