[Resolved] Intermittent 500 error

egg_

I'm getting an intermittent 500 error (internal server error) on a page on a site (linux hosting). Happens maybe half the time I go to the page. I never get it on the server I have on my home machine (windows). The error log says:

Premature end of script headers

I've made sure all the endline characters are Unix rather than Windows. The page is slow, even on my home machine (is runs about 30 queries), but according to the hoster there are no limits set for mysql queries. php is running as cgi rather than an apache module.

Any suggestions? This is pretty important for me to get right, I've spent months on the project and now can't get it to work properly on the live server

The script isn't timing out, I don't think - it seems to be something else. Is it possible that the thread running php is gettig garbage collected or something before execution is finished?

lth2h

First, you should develop on the same platform and configuration as the production server.

Your problem could be caused by a number of things. Wrong permissions or not enough memory would be the first two I'd look for.

egg_

Permissions are ok - all files set to 755
How can I tell if there are memory problems? I'm no Linux expert -is there likely to be a log file somewhere I can tail, or a command like ps -aux that will show me what's being used? I don't have root access

egg_

Ok
I looked at the memory while running scripts using ps -aux over and over (I'm sure there's a better way than this ...) and the %MEM goes up to 99.9. Presumably this is a bad thing - is there any neater way to track the memory so I can show the hosting company what's happening?

tsinka

Hi,

as of PHP 4.3.2 you can use memory_get_usage inside a script to check how much memory the script itself uses. Add some memory_get_usage calls in your scripts and print out the usage. Print out the value of each memory_get_usage call (espacially in loops) and use flush() to force the data to be sent to the browser immediately.

Just executing SQL queries shouldn't cause such problems so I assume that you might have problems with arrays becoming very huge or something like that.

Thomas

egg_

Found the problem, with the help of the zend profiler - one line of my code was running an eregi() on the whole page, which was taking up 80% of the execution time

Did the same thing in a more efficient way, problem solved

Thanks for the help