Another set of slides from a Benoit Jacquemont talk I would have loved to see. My high level summary
Don’t forget that your PHP program isn’t talking with anything directly, all activity goes through the your operating system’s kernel, and there are tools (
straceon linux) for looking at the system calls your program is indirectly making
Tangentially, I also recently came acros php-strace, a composer package that wraps up the logic of using strace to diagnose PHP segmentation faults.