Fix metric RootCoordInsertChannelTimeTick (#23236)

Signed-off-by: Nlongjiquan <jiquan.long@zilliz.com>

internal/rootcoord/timeticksync.go

@@ -22,8 +22,6 @@ import (
 	"sync"
 	"time"
 
-	"go.uber.org/zap"
-
 	"github.com/milvus-io/milvus-proto/go-api/commonpb"
 	"github.com/milvus-io/milvus-proto/go-api/msgpb"
 	"github.com/milvus-io/milvus/internal/log"
@@ -35,6 +33,7 @@ import (
 	"github.com/milvus-io/milvus/internal/util/timerecord"
 	"github.com/milvus-io/milvus/internal/util/tsoutil"
 	"github.com/milvus-io/milvus/internal/util/typeutil"
+	"go.uber.org/zap"
 )
 
 var (
@@ -300,6 +299,13 @@ func (t *timetickSync) startWatch(wg *sync.WaitGroup) {
 
 // SendTimeTickToChannel send each channel's min timetick to msg stream
 func (t *timetickSync) sendTimeTickToChannel(chanNames []string, ts typeutil.Timestamp) error {
+	func() {
+		sub := tsoutil.SubByNow(ts)
+		for _, chanName := range chanNames {
+			metrics.RootCoordInsertChannelTimeTick.WithLabelValues(chanName).Set(float64(sub))
+		}
+	}()
+
 	msgPack := msgstream.MsgPack{}
 	baseMsg := msgstream.BaseMsg{
 		BeginTimestamp: ts,
@@ -323,10 +329,6 @@ func (t *timetickSync) sendTimeTickToChannel(chanNames []string, ts typeutil.Tim
 		return err
 	}
 
-	sub := tsoutil.SubByNow(ts)
-	for _, chanName := range chanNames {
-		metrics.RootCoordInsertChannelTimeTick.WithLabelValues(chanName).Set(float64(sub))
-	}
 	return nil
 }