WSOD for a drupal page. How to debug using gdb?

Question

I got a WSOD (white screen of death) in my Drupal site for a single page for a single user. I have learned that it is due to segmentation error. I couldnt spot where the error is?? How do I debug my PHP code using gdb???

this is not twitter, dont need to #tag :P – Strae Mar 25 '11 at 08:00 — Strae, Mar 25 '11 at 08:00

score 2 · Answer 1 · answered Mar 26 '11 at 01:18

In extreme circumstances, I end up using Linux strace, but I do this mainly when the issue concerns internal stuff (such as headers, stack issues and crashes).

The more PHP-esque way is to use xdebug, since it's specifically for PHP.

To use GDB, use like any other program you would use under GDB. If you can't get that far, I'm pretty sure you won't get far in actually using GDB either.

Oh, and here's a life-saver PHP snippet:

function the_end(){
    if(($err=error_get_last()))
        die('<pre>'.print_r($err,true).'</pre>');
}
register_shutdown_function('the_end');

Note 1: If you're dealing with server crashes, there's a good chance the above won't work. This is quite rare though.

Note 2: If register_shutdown_function is already used elsewhere, be sure to repeat it, in order to ensure final execution, example:

function my_other_final_function(){ /* ... */ }
register_shutdown_function('my_final_function');

function the_end(){ /* ... */ }
function the_end2(){ register_shutdown_function('the_end'); }
register_shutdown_function('the_end2');

score 0 · Answer 2 · answered Mar 25 '11 at 08:02

0

I dont know how to do it with gdb, but this could be usefull:

index.php
error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);

And i guess XDebug could help you further

answered Mar 25 '11 at 08:02

Strae

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The linked page is btw the first result when googling for "Drupal wsod"... :) – Berdir Mar 25 '11 at 09:18
Yeah, except your doing it like me and accidently leave an exit() call somewhere in your module ;) – Berdir Mar 25 '11 at 09:24

score 0 · Answer 3 · answered Mar 28 '11 at 17:48

0

I tried to set display_errors true for the site which didnt work for me. But luckily I didnt have to go for the debugging, issue was with view that I had created.

Thank you all

answered Mar 28 '11 at 17:48

nirmal mohan

1

score -1 · Answer 4 · answered Mar 26 '11 at 00:59

-1

The error is most likely in you web server error logs. Look there first.

answered Mar 26 '11 at 00:59

Dave

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If it's a segmentation fault, as described in the post, the web server's error logs aren't going to be at all useful. – ceejayoz Mar 28 '11 at 17:59

WSOD for a drupal page. How to debug using gdb?

4 Answers4