Adventures & experiences in contemporary technology
My online travel photo gallery is a self-coded set of PHP scripts that read data from tables in a MySQL database. These tables are built from input XML files using a Perl script that itself creates and executes an SQL script. The Perl script also does some image processing using GraphicsMagick commands to resize images and to add copyright information and image framing. Because this processed one image at a time sequentially, it was taking several minutes to complete and only partly used the capacity of the PC that I used.
This led me to look at adding parallel processing and that is what brought me to looking at the Parallel::ForkManager Perl module. An alternative approach might have been to add new images in such a way as not to need the full run involving hundreds of image files, but that will take more work and I fancied having a look at parallelising things anyway.
If it was not there already, the first act would have been to install build-essential to get access to the cpan command. The following command accomplishes this:
sudo apt-get install build-essential
Once that is there, the cpan command needs to be run and some questions answered to get things going. The first question to answer is whether you want setup to be as automated as possible and the default answer of yes worked for me. The next question to answer regards the approach that cpan takes when installing modules and I chose sudo here (local::lib is the default value and manual is another option). After this, cpan drops into its own command shell. Here, I issued two more commands to continue the basic setup by updating CPAN.pm to the latest version and adding Bundle::CPAN to optimise the module further:
make install
install Bundle::CPAN
Continuing the last of these may need extra intervention to confirmation the suggested default of exit at one point in its operation and that takes a little time to complete. It is after this that Parallel::ForkManager can be installed using the following command:
install Parallel::ForkManager
That completed quickly and the cpan shell was exited using its exit command. Then, the new module was available in scripting after that. The actual use of this module is something that hope to describe in another post so I am ending this one here and the same process is just as applicable to setting up cpan and adding any other Perl CPAN module.
Please try cpanm. It’s way easier to use than cpan
Just had to do this again and only needed to issue the following command once cpan had done its business:
cpan Parallel::ForkManager
The script that I was running worked fine after that.