Subject: Re: ypserv -d vs. nsswitch
To: Jason Thorpe <email@example.com>
From: Bill Sommerfeld <firstname.lastname@example.org>
Date: 12/22/1999 14:25:25
> > Definitely. But do we need to have this on by default? How many of these
> > old clients are out there?
> who knows... but it certainly doens't hurt anything to have it turned on!
Actually, it can conceivably hurt.
ypserv does a blocking call to gethostbyname() while processing the
remote request. if a nameserver involved in the resolution is down,
it may take multiple seconds for that call to return; during that
time, ypserv will not process *any* other requests from any other
client, leading to sluggish/laggy/etc. behavior as perceived by any
system using that ypserv as its master.
Fundamental distributed systems robustness principle:
- servers should not make blocking remote calls to other servers,
because it makes them vulnerable to denying service when all the
worker threads get hung up waiting for responses..