Caffe2: serialize init for parallel workers
Caffe2: serialize init for parallel workers

Summary: Caffe2: serialize init for parallel workers

Reviewed By: kevinwilfong

Differential Revision: D6862119

fbshipit-source-id: 805b2971eca4501977950420565bd9ea37dc0f6c

xzturn/caffe2,Yangqing/caffe2,xzturn/caffe2,xzturn/caffe2,xzturn/caffe2,Yangqing/caffe2,xzturn/caffe2,Yangqing/caffe2,Yangqing/caffe2,caffe2/caffe2,Yangqing/caffe2