It all started when I decided to optimize image slicing algorithm for a new feature on UMapper – and since GD is quite RAM-intensive, I needed to check actual memory consumption, and the obvious choice to do so was PHP’s memory_get_usage() function. However, it failed to produce accurate results – it seemed like images loaded into memory weren’t accounted by the function (RAM was still used ).
As it turned out, whoever prepared official php5-gd package, compiles against original GD, and not using PHP5 bundled version of the library. I actually wasn’t aware about the fork, but here is explanation from GD Official Site:
The PHP version of gd offers features similar to and sometimes in addition to those included in the latest version of gd found here as well as many bug fixes not present in the latest GD release. If you are working with PHP, using the built-in gd of PHP 4.3.0 or better is recommended.
We are working to merge the changes done in the PHP GD in the normal GD library.
Well, I was pretty sure that unexpected behavior was caused by using original GD library instead of bundled one. So I decided to remove php5-gd package, recompile php5 from sources, and install updated GD package – which is exactly what gets bundled with PHP5 on other distributions.
Google is my friend, so here is a walkthrough:
# Install build tools, debian helpers and fakeroot
apt-get install build-essential debhelper fakeroot
# Get PHP source (it should go into /usr/src)
apt-get source php5
# Install all packages required to build PHP5
apt-get build-dep php5
#Now what we need is to update compile options,
# so we need to edit debian/rules file:
# locate the line having “–with-gd=shared,/usr –enable-gd-native-ttf \”
# replace with “–with-gd=shared –enable-gd-native-ttf \”
# that’s remove reference to /usr so that bundled library is used
# compile (drink some coffee, walk you dog, see the latest House episode)
# install the new php5-gd package
dpkg -i php5-gd_5.2.6.dfsg.1-3ubuntu4.2_i386.deb
# finally restart apache
That’s it – you should be able to see «bundled» near the GD version in the phpinfo() output. Well, that’s not the only gain – it solves problem with memory_get_usage() as well
Now, once I had memory_get_usage() working correctly, back to optimization..