[ic] Re: ALERT: bad pipe signal received for /page.html

Kevin Walsh kevin at cursor.biz
Mon Dec 11 20:49:19 EST 2006

Josh Lavin <josh at myprivacy.ca> wrote:
> Is plain CGI really as fast as mod_perl or mod_interchange? That'd be  
> my only concern with switching back to CGI+rewrites.
> Maybe it is ok -- see mod_interchange's README:
> "The Interchange link protocol has been
> implemented via an Apache module which
> saves us the (small) overhead
> of the execution of a CGI program."
The overhead referred to is the time taken to fork and exec the CGI
executable.  The executable file itself will most likely be cached,
on even lightly loaded systems, so there's no great concern over the
time it takes to open and read the CGI program prior to execution.

I've never been a great fan of rewrite rules, and there's a small
overhead to be saved there too.

Apart from any perceived efficiency enhancements, and pretty URIs
without rewrites, mod_interchange provides a couple of facilities
such as connection retries, failover to a backup Interchange server
and a request drop list etc., that are not available to CGI link

Mod_interchange is only available for use with Apache 1.3, but that's
not a massive problem.  Gentoo, for example, will install and maintain
Apache 1.3 instead of 2.x if you ask it to.

There's never been any demand for mod_interchange on Apache 2.x, which
is the main reason why it's still only available on 1.3.  I maintain
mod_interchange because I find it useful.  If I need to use Apache 2.x
for some reason then I'll port it regardless of the demand, or lack

I assumed that the lack of demand for mod_interchange on Apache 2.x
was down to the availability of the Interchange::Link mod_perl module.
Interchange::Link shares the same advantages as mod_interchange but
seems to have its quirks.  I'm sure those will be ironed out in time,
as long as the problems are reported.

Any overhead saved by using mod_interchange can very quickly be eaten
up with sloppy page code, so it's much more important to get your pages
to be as efficient as possible, rather than worry about the relative
merits of the various link facilities.

www.interchange.rtfm.info uses mod_interchange, by the way.

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