ref: 3d25c25aeafcf7c186ff449201ef7c061db00192
parent: 30328b85f2f4bb89d71e38b15148859a3fad14a6
parent: c12b88ae43a3a6c2293555b5abaeb9d60904b7f9
author: sijchen <sijchen@cisco.com>
date: Mon Sep 5 18:41:07 EDT 2016
Merge pull request #2554 from ruil2/thread3
use pthread_condition instead of semaphores on apple platform