基础：
http://blog.csai.cn/user3/50125/archives/2009/35140.html
多进程：
http://www.ibm.com/developerworks/cn/linux/l-cn-gdbmp/index.html
多线程：
http://www.91linux.com/html/article/program/20070406/1441.html
break [linespec] thread [threadno]
http://www.linuxforum.net/forum/gshowflat.php?Cat=&Board=program&Number=692404&page=0&view=collapsed&sb=5&o=all