From: khaines@...
Date: 2008-01-14T00:04:53+09:00
Subject: Re: [ANN] Thin v0.5.2 Cheezburger released

On Sun, 13 Jan 2008, Thomas Hurst wrote:

> Is it infeasable to support preforking after the listen socket's been
> opened, so many processes serve off the same port?  I've done this for a
> while now with FastCGI and other Ruby servers.
>
> When I questioned Zed about it re mongrel a few years ago he mentioned
> something about IO streams getting confused, which I've never seen;
> perhaps OS-specific, on systems where concurrent accept() on a socket
> isn't supported?

The problem with this approach is really just that it's viability is an 
accident.  It's not described in any spec that I have ever seen on how 
Linux networks should behave.  It's not guaranteed to continue working, 
and there's no guarantee that it will continue to be implemented in a way 
that fairly distributes requests.

So yes, on some platforms (Linux), it works, and has worked for quite a 
while.  But IMHO, using it for anything important is risky, and if one's 
app gets enough traffic that it needs a cluster, it would seem to me that 
it's probably important enough to warrant using something that's actually 
designed to operate as a load balancer and that is guaranteed to be a load 
balancer in the future.


Kirk Haines