diff --git a/weed/filer/filechunks.go b/weed/filer/filechunks.go
index be18d45ac..7e97118a6 100644
--- a/weed/filer/filechunks.go
+++ b/weed/filer/filechunks.go
@@ -3,13 +3,10 @@ package filer
 import (
 	"bytes"
 	"fmt"
-	"github.com/chrislusf/seaweedfs/weed/wdclient"
-	"math"
-	"sort"
-	"sync"
-
 	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
 	"github.com/chrislusf/seaweedfs/weed/util"
+	"github.com/chrislusf/seaweedfs/weed/wdclient"
+	"math"
 )
 
 func TotalSize(chunks []*filer_pb.FileChunk) (size uint64) {
@@ -164,112 +161,16 @@ func logPrintf(name string, visibles []VisibleInterval) {
 	*/
 }
 
-var bufPool = sync.Pool{
-	New: func() interface{} {
-		return new(VisibleInterval)
-	},
-}
-
-func MergeIntoVisibles(visibles []VisibleInterval, chunk *filer_pb.FileChunk) (newVisibles []VisibleInterval) {
-
-	newV := newVisibleInterval(chunk.Offset, chunk.Offset+int64(chunk.Size), chunk.GetFileIdString(), chunk.Mtime, 0, chunk.Size, chunk.CipherKey, chunk.IsCompressed)
-
-	length := len(visibles)
-	if length == 0 {
-		return append(visibles, newV)
-	}
-	last := visibles[length-1]
-	if last.stop <= chunk.Offset {
-		return append(visibles, newV)
-	}
-
-	logPrintf("  before", visibles)
-	// glog.V(0).Infof("newVisibles %d adding chunk [%d,%d) %s size:%d", len(newVisibles), chunk.Offset, chunk.Offset+int64(chunk.Size), chunk.GetFileIdString(), chunk.Size)
-	chunkStop := chunk.Offset + int64(chunk.Size)
-	for _, v := range visibles {
-		if v.start < chunk.Offset && chunk.Offset < v.stop {
-			t := newVisibleInterval(v.start, chunk.Offset, v.fileId, v.modifiedTime, v.chunkOffset, v.chunkSize, v.cipherKey, v.isGzipped)
-			newVisibles = append(newVisibles, t)
-			// glog.V(0).Infof("visible %d [%d,%d) =1> [%d,%d)", i, v.start, v.stop, t.start, t.stop)
-		}
-		if v.start < chunkStop && chunkStop < v.stop {
-			t := newVisibleInterval(chunkStop, v.stop, v.fileId, v.modifiedTime, v.chunkOffset+(chunkStop-v.start), v.chunkSize, v.cipherKey, v.isGzipped)
-			newVisibles = append(newVisibles, t)
-			// glog.V(0).Infof("visible %d [%d,%d) =2> [%d,%d)", i, v.start, v.stop, t.start, t.stop)
-		}
-		if chunkStop <= v.start || v.stop <= chunk.Offset {
-			newVisibles = append(newVisibles, v)
-			// glog.V(0).Infof("visible %d [%d,%d) =3> [%d,%d)", i, v.start, v.stop, v.start, v.stop)
-		}
-	}
-	newVisibles = append(newVisibles, newV)
-
-	logPrintf("  append", newVisibles)
-
-	for i := len(newVisibles) - 1; i >= 0; i-- {
-		if i > 0 && newV.start < newVisibles[i-1].start {
-			newVisibles[i] = newVisibles[i-1]
-		} else {
-			newVisibles[i] = newV
-			break
-		}
-	}
-	logPrintf("  sorted", newVisibles)
-
-	return newVisibles
-}
-
 // NonOverlappingVisibleIntervals translates the file chunk into VisibleInterval in memory
 // If the file chunk content is a chunk manifest
 func NonOverlappingVisibleIntervals(lookupFileIdFn wdclient.LookupFileIdFunctionType, chunks []*filer_pb.FileChunk, startOffset int64, stopOffset int64) (visibles []VisibleInterval, err error) {
 
 	chunks, _, err = ResolveChunkManifest(lookupFileIdFn, chunks, startOffset, stopOffset)
 
-	visibles2 := readResolvedChunks(chunks)
-
-	if true {
-		return visibles2, err
-	}
-
-	sort.Slice(chunks, func(i, j int) bool {
-		if chunks[i].Mtime == chunks[j].Mtime {
-			filer_pb.EnsureFid(chunks[i])
-			filer_pb.EnsureFid(chunks[j])
-			if chunks[i].Fid == nil || chunks[j].Fid == nil {
-				return true
-			}
-			return chunks[i].Fid.FileKey < chunks[j].Fid.FileKey
-		}
-		return chunks[i].Mtime < chunks[j].Mtime // keep this to make tests run
-	})
-
-	for _, chunk := range chunks {
-
-		// glog.V(0).Infof("merge [%d,%d)", chunk.Offset, chunk.Offset+int64(chunk.Size))
-		visibles = MergeIntoVisibles(visibles, chunk)
-
-		logPrintf("add", visibles)
-
-	}
-
-	if len(visibles) != len(visibles2) {
-		fmt.Printf("different visibles size %d : %d\n", len(visibles), len(visibles2))
-	} else {
-		for i := 0; i < len(visibles); i++ {
-			checkDifference(visibles[i], visibles2[i])
-		}
-	}
+	visibles = readResolvedChunks(chunks)
 
 	return
-}
 
-func checkDifference(x, y VisibleInterval) {
-	if x.start != y.start ||
-		x.stop != y.stop ||
-		x.fileId != y.fileId ||
-		x.modifiedTime != y.modifiedTime {
-		fmt.Printf("different visible %+v : %+v\n", x, y)
-	}
 }
 
 // find non-overlapping visible intervals
@@ -286,19 +187,6 @@ type VisibleInterval struct {
 	isGzipped    bool
 }
 
-func newVisibleInterval(start, stop int64, fileId string, modifiedTime int64, chunkOffset int64, chunkSize uint64, cipherKey []byte, isGzipped bool) VisibleInterval {
-	return VisibleInterval{
-		start:        start,
-		stop:         stop,
-		fileId:       fileId,
-		modifiedTime: modifiedTime,
-		chunkOffset:  chunkOffset, // the starting position in the chunk
-		chunkSize:    chunkSize,
-		cipherKey:    cipherKey,
-		isGzipped:    isGzipped,
-	}
-}
-
 func min(x, y int64) int64 {
 	if x <= y {
 		return x