clancy_1@xxxxxxxxxxxx wrote:
On Thu, 07 Jan 2010 22:48:59 -0500, robert@xxxxxxxxxxxxx (Robert Cummings) wrote:
clancy_1@xxxxxxxxxxxx wrote:
Thank you all for your comments. I did not know about bytecode caches. They're an
interesting concept, but if I am interpreting the paper
http://itst.net/654-php-on-fire-three-opcode-caches-compared correctly they only double
the average speed of operation, which is rather less than I would have anticipated.
I strongly advise that you take the time to try a bytecode cache. Within
linux environments I am partial to eaccelerator. In IIS environments I
now use WinCache from Microsoft. From my own observations with a
multitude of different types of PHP web applications I find that the
speed gain is closer to 5 times faster on average.
Five times faster is certainly more attractive than twice as fast. But under what
circumstances is this achieved? Unfortunately these days it is difficult to find any solid
information on how things actually work, but my impression is that caches only work for
pages which are frequently accessed. If this is correct, and (as I suspect) somebody looks
at my website once an hour, the page will not be in the cache, so it won't help. Also one
of the more popular parts of this website is my photo album, and for this much of the
access time will be the download time of the photos. Furthermore as each visitor will look
at a different set of photos, even with heavy access it is unlikely that any given photo
would be in a cache.
A particular cache of bytecode is usually pushed out of memory when the
configured maximum amount of memory for the bytecode cache is about to
be exceeded. Additionally, the particular cache that gets eliminated is
usually the oldest or least used cache. Given this, and your purported
usage patterns, your pages will most likely remain in the cache until
such time as you update the code or restart the webserver.
Despite these comments the access times for my websites seem to be pretty good --
certainly a lot better than many commercial websites -- but have a look at
http://www.corybas.com/, and see what you think. (I am in the process of updating this,
and know that the technical notes are not currently working, but there is plenty there to
show you what I'm trying to do.)
I'm not disputing your good enough statistics. I'm merely asserting that
a bytecode cache will resolve your concerns about file access times when
your code is strewn across many compartmentalized files. In addition, I
am advising that it is good practice to always install a bytecode cache.
One of the first things I do when setting up a new system is to ensure I
put an accelerator in place. Once it's in place, no matter how many
pages or sub sites I put up, the accelerator is already in place and
providing benefits.
Cheers,
Rob.
--
http://www.interjinn.com
Application and Templating Framework for PHP
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
