Consider using 127.0.0.1 instead of localhost and binding to 127.0.0.1 as well.

This is perhaps controversial, but there are a variety of problems with counting on dns hostname resolution, especially for locahost.

1. It can often be slow, slow under concurrency, or slow under specific conditions.
2. It can often not work at all - when on a VPN, with weird DNS hijacking hi-jinks, when you have a real hostname for you machines, a custom /etc/hosts file, OS's run their own local/funny DNS server services.
3. This makes coming to HBase for new devs a hit or miss experience and if you miss, dealing with an diagnosing the issues is a large endeavor and not straight forward or transparent.
4.  99% of the difference doesn't matter in most cases - except that 127.0.0.1 works and is fast pretty much universally.