pooling []byte

reduce the number of requests to make([]byte)

go/weed/weed_server/volume_server_handlers_read.go

@@ -66,6 +66,7 @@ func (vs *VolumeServer) GetOrHeadHandler(w http.ResponseWriter, r *http.Request)
 	cookie := n.Cookie
 	count, e := vs.store.ReadVolumeNeedle(volumeId, n)
 	glog.V(4).Infoln("read bytes", count, "error", e)
+	defer n.ReleaseMemory()
 	if e != nil || count <= 0 {
 		glog.V(0).Infoln("read error:", e, r.URL.Path)
 		w.WriteHeader(http.StatusNotFound)