Re: [PHP] Re: php-general Digest 25 Jan 2008 07:59:28 -0000 Issue 5255

On Fri, January 25, 2008 12:59 pm, Eric Butera wrote:
On Jan 25, 2008 1:39 PM, Richard Lynch <ceo@xxxxxxxxx> wrote:
On Fri, January 25, 2008 7:27 am, Eric Butera wrote:
I think the memory size can (sort of) be determined by width *
height
* bits * channels / 8. I've never found anything better than
that.
There are a few comments on the php site in the gd section about
such
things but I've never seen it work 100%. I always set the real
memory
limit much higher than what I say the max is for the memory size
just
in case it gets an image that could break it. At least that
stopped
the friendly white screens of death. :)

If anyone has better ways of handling this I'd love to hear them.

Don't try to do the thumb-nail in real-time for the user that
uploads it.

They already know what the image looks like. :-)

Off-load that task to a separate cron job, run from CLI, which can
use:

php -q -d memory_limit 1000000000 thumbnail.php /path/to/image.jpg
/path/to/thumbnails/

This way, you are not letting your HTTP php processes chew up more
RAM
than they really should, and you can give the thumbnail script a GIG
(or more) of RAM to do whatever it needs to do.

Run that job often enough, and the thumbnail will be available "fast
enough" for the users who don't know what the image looks like.


Hi Richard,

The way I handle thumbnail creation is (this is generalized) but an if
statement that says

if (thumbnail file name not in db) {
set img src to a script that renders thumbnail, saves it
somewhere, and updates the db record so that this never happens again
until i reset it (in case they want to change thumb sizes)
} else {
raw link to image
}

The main issue is that when someone uploads an image for a piece of
content or a product image I need to scale it down to a sane amount of
~800 w/h before I even allow it on the site. From there I use the
thumbnail on demand.

Perhaps you could check the size of the image in another elseif() in
the middle and handle over-size images specially.

I'm not sure the cron job idea is the best for my situation though.
When a client uploads a product image in a store they just paid for
they expect it to show up before 3am when the server load is down. If
I run it every 15 minutes I really don't see the advantage of that
seeing as I can do an ini_set on the memory limit at any point I
decide since it is my server. Cron for 15 minutes still means at 3pm
which we are at a heavy load the 1g script would kick in.

The difference is that you have one (1) CLI script using 1G, instead
of *EVERY* Apache child using 1G...

You could also run the CLI at nice -n 19, so that it is super low
priority, and then not worry about server load. :-)

Separating the process off from your main logic gives you all sorts of
flexibility that just isn't there when you try to do it inline.

If you are using fast_cgi instead of mod_php, I'm not sure this helps
much in terms of RAM usage...

The good thing though is that most people just set up their
store/content and don't really update it too much after that. That is
why I'm after a solution that allows me to figure out the memory size
so I can just tell them if they need to lower the resolution a bit and
try again.

I'll keep this cron solution in mind though, could come in handy at
some point.



--
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Know what I want?
I want you to buy a CD from some indie artist.
http://cdbaby.com/from/lynch
Yeah, I get a buck. So?
.

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