Handling large strings in PHP
We recently needed to write an algorithm to unpack a specific file from a proprietary archive format.
The fun part is that the initial task quickly transformed into a research task as our colleague Michael wanted to dig deeper in the topic. Here is the story behind the performance boost.
I never worked with binary files before in PHP so I decided to first get it working and care about optimisations later.
My straight forward approach of using file_get_contents and normal string operations resulted in very low performing and memory hungry process.
For getting a 10kb file out of an 2MB archive the algorithm took ~1.200ms and ~14mb memory at its peak.
This had to be optimized ... and I succeeded to bring it down to 30ms and 1MB memory at its peak ...
