diff --git a/weed/server/filer_server_handlers_write_upload.go b/weed/server/filer_server_handlers_write_upload.go
index cc9bb0dc0..32a722507 100644
--- a/weed/server/filer_server_handlers_write_upload.go
+++ b/weed/server/filer_server_handlers_write_upload.go
@@ -10,6 +10,7 @@ import (
 	"sort"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/chrislusf/seaweedfs/weed/filer"
@@ -38,11 +39,21 @@ func (fs *FilerServer) uploadReaderToChunks(w http.ResponseWriter, r *http.Reque
 	var uploadErr error
 
 	var wg sync.WaitGroup
+	var bytesBufferCounter int64
+	bytesBufferLimitCond := sync.NewCond(new(sync.Mutex))
 	for {
 
-		// need to throttle this for large files
+		// need to throttle used byte buffer
+		bytesBufferLimitCond.L.Lock()
+		for atomic.LoadInt64(&bytesBufferCounter) >= 4 {
+			glog.V(4).Infof("waiting for byte buffer %d", bytesBufferCounter)
+			bytesBufferLimitCond.Wait()
+		}
+		atomic.AddInt64(&bytesBufferCounter, 1)
+		bytesBufferLimitCond.L.Unlock()
+
 		bytesBuffer := bufPool.Get().(*bytes.Buffer)
-		defer bufPool.Put(bytesBuffer)
+		glog.V(4).Infof("received byte buffer %d", bytesBufferCounter)
 
 		limitedReader := io.LimitReader(partReader, int64(chunkSize))
 
@@ -52,6 +63,9 @@ func (fs *FilerServer) uploadReaderToChunks(w http.ResponseWriter, r *http.Reque
 
 		// data, err := ioutil.ReadAll(limitedReader)
 		if err != nil || dataSize == 0 {
+			bufPool.Put(bytesBuffer)
+			atomic.AddInt64(&bytesBufferCounter, -1)
+			bytesBufferLimitCond.Signal()
 			return nil, md5Hash, 0, err, nil
 		}
 		if chunkOffset == 0 && !isAppend(r) {
@@ -59,13 +73,21 @@ func (fs *FilerServer) uploadReaderToChunks(w http.ResponseWriter, r *http.Reque
 				chunkOffset += dataSize
 				smallContent = make([]byte, dataSize)
 				bytesBuffer.Read(smallContent)
+				bufPool.Put(bytesBuffer)
+				atomic.AddInt64(&bytesBufferCounter, -1)
+				bytesBufferLimitCond.Signal()
 				break
 			}
 		}
 
 		wg.Add(1)
 		go func(offset int64) {
-			defer wg.Done()
+			defer func() {
+				bufPool.Put(bytesBuffer)
+				atomic.AddInt64(&bytesBufferCounter, -1)
+				bytesBufferLimitCond.Signal()
+				wg.Done()
+			}()
 
 			chunk, toChunkErr := fs.dataToChunk(fileName, contentType, bytesBuffer.Bytes(), offset, so)
 			if toChunkErr != nil {