[CentOS] Slow performance

[Scott Lamb]

On Apr 30, 2007, at 5:07 PM, Ashley M. Kirchner wrote:
>    I did a test running convert, single processor and got the  
> following timing:
>
>        ImageMagick 'convert', 1 process, JPEG (command line)
>        real    8m35.515s
>        user    6m18.674s
>        sys     1m46.344s
>
>
>    Then I wrote a small PHP script that does the same thing (read  
> image, resize with constrain) and ran it through the command line,  
> and got this:
>
>        PHP, 1 process, JPEG (through PHP CLI)
>        real    36m17.260s
>        user    35m38.972s
>        sys     0m30.651s
>
>
>    Why oh why is it so much slower?!  Is there something  
> inheritedly slow within PHP that causes it to be so much slower  
> (which in turn causes the Apache process to also take an incredible  
> amount of time to finish the same task)?

Interesting. I'm not sure, as I don't use PHP. You might have better  
luck getting an answer if you post your test scripts to a PHP list.

A few things I might do if I were trying to diagnose this:

- throw in a few getrusage()s to see which section of the script is  
using the most time - maybe I'd get lucky and see one obviously wrong
- ltrace shows all calls to shared libraries - maybe it could uncover  
something weird
- use whatever profiling tool is available for profiling PHP scripts.  
(In Python, I'm fond of hotshot.)
- find out what underlying library they're using and try it from a  
different language (Python, C, whatever) to see if the library or PHP  
is the problem.
- compile the PHP interpreter itself with profiling and run it  
through gprof to where the time went.

-- 
Scott Lamb <http://www.slamb.org/>