LMHB是11gR2中新引入的后台进程，官方文档的介绍是Global Cache/Enqueue Service Heartbeat Monitor，Monitor the heartbeat of LMON, LMD, and LMSn processes，LMHB monitors LMON, LMD, and LMSn processes to ensure they are running normally without blocking or spinning。
本文转自maclean_007 51CTO博客，原文链接:http://blog.51cto.com/maclean/1278174
