Make write binlog in parallel (#26325)

Signed-off-by: NCongqi Xia <congqi.xia@zilliz.com>

internal/datanode/flush_manager.go

@@ -27,6 +27,7 @@ import (
 	"github.com/samber/lo"
 	"go.uber.org/atomic"
 	"go.uber.org/zap"
+	"golang.org/x/sync/errgroup"
 
 	"github.com/milvus-io/milvus-proto/go-api/v2/commonpb"
 	"github.com/milvus-io/milvus-proto/go-api/v2/msgpb"
@@ -670,7 +671,15 @@ func (t *flushBufferInsertTask) flushInsertData() error {
 	defer cancel()
 	if t.ChunkManager != nil && len(t.data) > 0 {
 		tr := timerecord.NewTimeRecorder("insertData")
-		err := t.MultiWrite(ctx, t.data)
+		group, ctx := errgroup.WithContext(ctx)
+		for key, data := range t.data {
+			key := key
+			data := data
+			group.Go(func() error {
+				return t.Write(ctx, key, data)
+			})
+		}
+		err := group.Wait()
 		metrics.DataNodeSave2StorageLatency.WithLabelValues(fmt.Sprint(paramtable.GetNodeID()), metrics.InsertLabel).Observe(float64(tr.ElapseSpan().Milliseconds()))
 		if err == nil {
 			for _, d := range t.data {