Kevin Schroeder: Setting max_input_time (with data!)

Kevin Schroeder has a new post to his site today wondering about the "max_input_time" setting for PHP and why some recommend it being a large number despite the (usually) fast time PHP has accepting input.

I asked a question on Twitter on why some of the recommend max_input_time settings seem to be ridiculously large. Some of the defaults I've seen have been upwards of 60 seconds. However, after thinking about it I was a little confused as to why a C program (i.e. PHP) would take so long to process string input. The reason I was thinking about this was because I was thinking about ways to protect PHP from denial of service attacks.

So he ran some tests to see just how effective changes in this setting could be and how much time a typical PHP request would need to take in input. Using a Zend Framework 2 HTTP client, he simulated POSTS and tracked the start and end times for a file upload. He includes the timing results in the post based on both this setup and a change to only post regular text-based form data.