Fix for multiple concurrent ephemeral consumer requests in clustered mode with max consumers set.

Signed-off-by: Derek Collison <derek@nats.io>

server/jetstream_cluster.go

@@ -4050,14 +4050,12 @@ func (s *Server) jsClusteredConsumerRequest(ci *ClientInfo, acc *Account, subjec
 	ca := &consumerAssignment{Group: rg, Stream: stream, Name: oname, Config: cfg, Subject: subject, Reply: reply, Client: ci, Created: time.Now().UTC()}
 	eca := encodeAddConsumerAssignment(ca)
 
-	// Mark this as pending if a durable.
-	if isDurableConsumer(cfg) {
-		if sa.consumers == nil {
-			sa.consumers = make(map[string]*consumerAssignment)
-		}
-		ca.pending = true
-		sa.consumers[ca.Name] = ca
+	// Mark this as pending.
+	if sa.consumers == nil {
+		sa.consumers = make(map[string]*consumerAssignment)
 	}
+	ca.pending = true
+	sa.consumers[ca.Name] = ca
 
 	// Do formal proposal.
 	cc.meta.Propose(eca)

server/jetstream_cluster_test.go

@@ -7640,6 +7640,59 @@ func TestJetStreamClusterMaxConsumers(t *testing.T) {
 	}
 }
 
+func TestJetStreamClusterMaxConsumersMultipleConcurrentRequests(t *testing.T) {
+	c := createJetStreamClusterExplicit(t, "JSC", 3)
+	defer c.shutdown()
+
+	nc, js := jsClientConnect(t, c.randomServer())
+	defer nc.Close()
+
+	cfg := &nats.StreamConfig{
+		Name:         "MAXCC",
+		Storage:      nats.MemoryStorage,
+		Subjects:     []string{"in.maxcc.>"},
+		MaxConsumers: 1,
+		Replicas:     3,
+	}
+	if _, err := js.AddStream(cfg); err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	si, err := js.StreamInfo("MAXCC")
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if si.Config.MaxConsumers != 1 {
+		t.Fatalf("Expected max of 1, got %d", si.Config.MaxConsumers)
+	}
+
+	startCh := make(chan bool)
+	var wg sync.WaitGroup
+
+	for n := 0; n < 10; n++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			nc, js := jsClientConnect(t, c.randomServer())
+			defer nc.Close()
+			<-startCh
+			js.SubscribeSync("in.maxcc.foo")
+		}()
+	}
+	// Wait for Go routines.
+	time.Sleep(250 * time.Millisecond)
+
+	close(startCh)
+	wg.Wait()
+
+	var names []string
+	for n := range js.ConsumerNames("MAXCC") {
+		names = append(names, n)
+	}
+	if nc := len(names); nc > 1 {
+		t.Fatalf("Expected only 1 consumer, got %d", nc)
+	}
+}
+
 // Support functions
 
 // Used to setup superclusters for tests.