rndc reconfig delays

[Rob Foehl]

I've been experimenting with loading a large number of master zones (on 
the order of 250,000) in a single BIND instance, and have noticed that 
'rndc reconfig' with this many zones loaded can take a very long time to 
determine that it has little or nothing to do.  Worse, the server stops 
answering other requests for the duration, in both threaded and 
non-threaded builds -- I'm testing with 64 bit builds of both 9.7.0-P1 and 
9.7.1-P2.

In the best case, a reconfig will take about 40 seconds to complete, and 
stalls the server for most of that time.  Loading zones in bulk is 
substantially slower, but is less of an issue for the intended use, and is 
more or less limited by the speed of the storage.

My next step is going to be to experiment with the rndc addzone/delzone 
feature in the 9.7.2 betas, which hopefully should avoid any need to 
attempt a reconfig during normal use.  That aside, is there anything else 
I could be doing to speed things up?

-Rob