php /fastcgi error (using GD, semaphore timeout)

[marc2003]

i have an index page which contains several mysql queries. i'm then using the results from these to call an image script using gd. i'm using a loop and calling the image script 31 times per page with different parameters each time.... eg

chart.php?t=12&u=4
chart.php?t=78&u1
etc

for the most part this works fine, but every now and then, sometimes 1, 2, 3 or even 4 of the 31 images won't show. refreshing the page sorts it but i was wondering what's causing this? this is the error i get in my fastcgi log

02/Jun/2007:20:34:31 +0100 SUID: 188 PUID: 188 RUID: 1 URI: /np/chart.php connect() = The semaphore timeout period has expired.

the image script itself is only a few lines of code and gets the parameters it needs from GET, no db queries being made.

so, any ideas? abyss problem or a php problem? :)

[aprelium]

marc2003,

This usually happens when PHP processes are overloaded. This is unfortunately a PHP related problem that has been reported several times in the past but they are still fixing it. Actually, PHP people have chosen to recode their own FastCGI layer (instead of using the original one published by fastcgi.com) and their implementation is not the best one ever written: it has some problems especially under high load (and if your computer is already busy doing something else).
_________________
Support Team
Aprelium - http://www.aprelium.com

[marc2003]

ok, thanks for the reply.

i was only testing on my home pc and it wasn't under any other load. i guess 30 odd simultaneous requests must be too much? :confused:

i might try and put a delay in my loop or something.....

[aprelium]

marc2003,

You can always switch PHP to CGI only. This is guaranteed to work fine.
_________________
Support Team
Aprelium - http://www.aprelium.com

[marc2003]

ah cool. thanks for your help.