fix race condition in index
fix race condition in index


Former-commit-id: 17342b8ee274ef69893dc8619d5b1a898d5cf1b8
larryxiao/peloton,ranxian/peloton,larryxiao/peloton-1,ranxian/peloton,omegaga/peloton,ranxian/peloton,omegaga/peloton,omegaga/peloton,amaliujia/CMUDB-peloton,omegaga/peloton,omegaga/peloton,amaliujia/CMUDB-peloton,larryxiao/peloton,amaliujia/CMUDB-peloton,ranxian/peloton,omegaga/peloton,larryxiao/peloton-1,larryxiao/peloton-1,amaliujia/CMUDB-peloton,amaliujia/CMUDB-peloton,larryxiao/peloton-1,larryxiao/peloton,larryxiao/peloton,larryxiao/peloton-1,larryxiao/peloton,amaliujia/CMUDB-peloton,ranxian/peloton,omegaga/peloton,larryxiao/peloton-1,larryxiao/peloton-1,larryxiao/peloton,amaliujia/CMUDB-peloton,larryxiao/peloton,ranxian/peloton