[ic] Perl and Threading

Henry Hartley henryhartley at westat.com
Thu Jun 22 14:03:23 EDT 2006

Andreas Grau wrote:
>> Here's the [snip] with Mike's reply at the bottom:
>> > So does this mean threaded Perl might be ok to use with IC now?
>> It might -- it runs fine as far as I can tell. But I don't know why
>> anyone would want to, as you pay a 15-30% speed penalty.

Thanks to those who responded.  I just didn't go back far enough.  I
know I'm answering Mike and not Andreas but here's one user's take on
the perl performance question.

I can say that while a 15-30% penalty sounds like a lot, it certainly
depends on at least a few other factors.  For instance, the difference
between running Interchange on something state of the art verses an
older, slower machine would probably be considerably more than 30%.  So,
comparing unthreaded perl on my old 2.4GHz P4 to threaded perl on one of
the newer, faster processors the threaded perl would probably be faster.
If responsiveness was acceptable on the old machine with untreaded perl,
I don't see how it would be unacceptable with threaded perl on a faster
machine.  Sure, for heavy loads you will want both and if I were
building a site that expected lots of traffic, it would justify the
extra cost of the hardware and the extra time to set up and maintain the
system.  This is just a guess but many Interchange sites probably rarely
see two concurrent users and for them it isn't going to matter as much.

Also, saving 15-30% in speed doesn't matter as much if things are
already fast enough.  That is, if a process adds a half second or two to
a page being loaded, it's not going to be noticed by most people.

The benefits to using the default Perl, while also modest, are that a
machine can be set up and maintained that much more easily.  Either way,
it's not going to be a deal breaker.  In my opinion, having the choice
is a Good Thing (TM).  If I spent the time to get used to Gentoo, it
would probably be worth the effort but I've been doing things "The Red
Hat Way" for so long, it's hard to switch.


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