Limit statsz updates to once every 5 seconds per client

server/client.go

@@ -285,7 +285,8 @@ type client struct {
 	tags    jwt.TagList
 	nameTag string
 
-	tlsTo *time.Timer
+	tlsTo      *time.Timer
+	lastStatsz time.Time
 }
 
 type rrTracking struct {
@@ -3398,6 +3399,15 @@ func (c *client) deliverMsg(prodIsMQTT bool, sub *subscription, acc *Account, su
 
 	client.mu.Lock()
 
+	// Limit statsz updates to once every 5 seconds per client.
+	if string(sub.subject) == "$SYS.SERVER.*.STATSZ" {
+		if time.Since(client.lastStatsz) < 5*time.Second {
+			client.mu.Unlock()
+			return false
+		}
+		client.lastStatsz = time.Now()
+	}
+
 	// Check if we have a subscribe deny clause. This will trigger us to check the subject
 	// for a match against the denied subjects.
 	if client.mperms != nil && client.checkDenySub(string(subject)) {

server/client_test.go

@@ -3055,3 +3055,16 @@ func TestInProcessAllowedConnectionType(t *testing.T) {
 		})
 	}
 }
+
+func TestClusterSetupMsgs(t *testing.T) {
+	numServers := 10
+	c := createClusterEx(t, true, 5*time.Millisecond, true, "cluster", numServers)
+	var totalOut int
+	for _, server := range c.servers {
+		totalOut += int(server.outMsgs)
+	}
+	totalExpected := numServers * numServers
+	if totalOut >= totalExpected {
+		t.Fatalf("Total outMsgs is %d, expected < %d\n", totalOut, totalExpected)
+	}
+}