http://www.cnblogs.com/P_Chou/archive/2012/07/13/semaphore-and-mutex-in-thread-sync.html
http://blog.csdn.net/wangweitingaabbcc/article/details/6833265
http://blog.csdn.net/wangweitingaabbcc/article/details/6833191
http://zhidao.baidu.com/link?url=V6C1K5f40ZMK6vk9kCKI_TqbwA5yoScDIxmQOSJYPWcRzvdJgAnOslICu8qeQl_O4CsHeU2OVivP40IBhM2GSq
http://blog.itpub.net/7416120/viewspace-867624/