线程同步（互斥量、条件变量、信号量、自旋锁、读写锁）

http://blog.163.com/huangguoqiang_123%40126/blog/static/14104311420125289822440/   写的很好

https://blog.csdn.net/jkx01whg/article/details/78119189

http://www.cnblogs.com/lonelycatcher/archive/2011/12/20/2294161.html