Delete the val that never used

It seems that the val "startTime" and "endTime" is never used, so delete them.

Author: WangTao <barneystinson@aliyun.com>

Closes #553 from WangTaoTheTonic/master and squashes the following commits:

4fcb639 [WangTao] Delete the val that never used

(cherry picked from commit 25a276dd21457fa0db76b6be93765682a50b784a)
Signed-off-by: Reynold Xin <rxin@apache.org>