Sendop use 100% cpu in async sync_mode.
Created by: gongweibao
It seems that VarHandle->wait consume 100% CPU.
25264 root 20 0 65.936g 0.034t 221644 R 100.3 16.3 66:01.27 python -u dist_se_resnext.py --role trainer --endpoints 127.0.0.1:18460,127.0.0.1:20429 --trainer_id 0 +
