Logging with Apache/PHP

[rmichael]

I have written a test stub plugin which is not working and I am attempting to debug. However, PHP does not seem to want to tell me what is wrong.

With my plugin installed in OJSROOT/plugins/generic/testPlugin, OJS simply loads a blank screen. If I remove it, all is well.

I have attempted to turn as much logging as possible by including in my virtualhost file:

php_value error_log /var/log/php/ojs-2.1.1-test-php_error_log
php_flag display_errors on
php_flag log_errors on
php_value error_reporting 6143

Errors are written to that file because, if I remove my plugin such that OJS works again, and I add "error_log("Test error log.");" to OJSROOT/index.php, the message appears in my custom error log.

I have also added "ini_set('display_errors')..." to the top of OJSROOT/index.php, but that hasn't had any effect either.

It could be true that PHP simply isn't generating any errors, despite OJS not working properly. But something different, and broken, is happening and I need to find out what.

Any advice on increasing the verbosity and debugging of either PHP or OJS?

Thanks.

[asmecher]

Hi Richard,

This is a frustrating attribute of PHP -- there are certain kinds of code syntax errors that will cause PHP to simply die without error messages. Usually this happens to me when I've added the wrong number of braces, e.g. closing an extra code block or something similar. For plugins, the easiest debugging strategy is to comment out large portions of the plugin and gradually add code back in until you find out which block causes PHP to die.

Regards,
Alec Smecher
Public Knowledge Project Team

[jalperin]

Richard,

Another thing that has gotten me in trouble in the past, when I made my first few plugins, is that I could copy code from another plugin. If two plugins try to register with the same name, this causes OJS to die without messages.

[rmichael]

That really is frustrating. Thanks for the quick response!

[rmichael]

Thanks Juan.

Although, I'm rather careful about copying code, especially because I prefer not to do it. It doesn't help me learn very much, it can lead to worse problems if one doesn't understand what has been copied, and I'm not easily convinced the other person has done things correctly in the first place.