Slow PHP script - automatic debug and diagnosis?

Question

How can I find out whether a PHP script goes bad and runs really slow when ran by hundreds of users every second, and better yet, is there any tool that could tell me approximately which part of the code slows me down? ...

I don't wish to post the code here (mainly because this question refers to something else and because it's a waste of space) and preferably never post it anywhere because it's actually a mess!... a mess that I understand and yes, i coded it, but still a mess which would insult anyone trying to comprehend it... so if you have any creative ideas, please let me know!

Cheers!

( thank you already for your incoming answers! )

Answer 1

Enable XDebug profiling, and send the resulting files through WinCacheGrind (Windows) or KCacheGrind (Linux).

This will allow you to see a breakdown of which functions get called most, and where the time is spent. Learning to use XDebug is a must for any serious PHP developer.

Here is a seemingly good tutorial on getting started with XDebug profiling.

Answer 2

You will need two tools

• a profiler (Google it)

i use this one at work :

http://www.nusphere.com/products/php_profiler.htm (commercial)

• a load tester

check this site for more info :

http://performance-testing.org/content/performance-testing-tools

Answer 3

I'd recommend to use a PHP profiler. Xdebug which is both PHP debugger and profiler can help a lot. There are also other debuggers, e.g. Zend Debugger.

To analyze profiling results you could also need a special tool. I used WinCacheGrind in Windows and KCachegrind in Linux.

Profiling report shows tons of useful information e.g. which lines of the source code were called how many times and which functions took the most of the execution time.