regionserver crashed and failover

regionserver crashed,it is too long time to notify hmaster.when hmaster know regionserver's shutdown,it is long time to fetch the hlog's lease.
hbase is a online db, availability is very important.
i have a idea to improve availability, monitor node to check regionserver's pid.if this pid not exsits,i think the rs down,i will delete the znode,and force close the hlog file.
so the period maybe 100ms.