On Sun, 26 Apr 2009, Louis Mamakos wrote:
There are other protocols and applications other than HTTP to web
servers. I don't
understand, for instance, how I'd use lighttpd to build an XMPP
server
that needs
to manage a large number of TCP connections. Likewise, "business
logic"
need not
be a heavyweight operation that hits a database, or even a disk
arm. An
XMPP
server might have lightweight per-connection state in memory for a
few
thousand
sessions.
Using an alternative to select(), like kqueue() is a huge win because
you don't
have to continually pass an indication of interest back and forth
across
the
kernel system call interface for each invocation. A small change
like
this can
avoid a lot of complexity in your system in managing multiple
instances
of
an application.
Fair enough, my example was web specific. The idea of using load
balancers to scale vertically is still valid for a lot of scenarios,
especially when business logic outweighs the processiong time for
connection handling by a long shot. My reply was mainly related to the
original post which I think addressed web application development.
After all, for many of these scenarios select does a better job than
threading or forking (even though that always depends on the
particular
task) but if select would have been good enough for everything,
/dev/poll, epoll, kqueue etc. would never have been developed.
-T
