One of the most common and frustrating errors encountered by PHP coders reads: “Fatal error: Allowed memory size of 8388608 bytes exhausted…” followed by something like “(tried to allocate XXXX bytes) in /home/www/file.module on line 12.” This fatal PHP error crops up because, by default, PHP has a memory usage limit of 8 MB for any given script. This is a good thing, actually, because you don’t want a rogue PHP script to bring down your server by hogging all the memory. But occasionally, you’ll have a PHP script that normally exceeds the 8 MB limit (say, for importing or uploading). To workaround the “Fatal error: Allowed memory size of 8388608 bytes exhausted…” error message, simply insert this line of code into your script at the top:
ini_set("memory_limit","16M");
This will set your memory limit to 16 MB, rather than 8 MB. You can, and should, fiddle with this number so that it is as low as possible without repeating that error message. This will only alter the memory limit for that particular PHP file.
Alternately, you can alter your php.ini file to up the memory limit. This will affect all scripts on your server. Simply open php.ini and find the line that reads “memory_limit” and alter it:
memory_limit=16M
I’ve noticed in my own PHP.ini file that my default is much higher at 128M. So, if I were to ever receive this error message it would read: “Fatal error: Allowed memory size of 134217728 bytes exhausted…” and obviously be a much bigger problem. But it has the same workaround as “Fatal error: Allowed memory size of 8388608 bytes exhausted…” or “Fatal error: Allowed memory size of 16777216 bytes exhausted…” or whatever. Apparently, the memory_limit default was upped from 8M to 16M in PHP 5.2.0 and is now 128M for PHP 5.3.0, which would explain why you may not get this error message at all.
You can also disable the memory limit by setting memory_limit to –1 in PHP.ini.
memory_limit=-1
This isn’t usually a good idea, though, for obvious reasons.
Note: You can also use the memory_limit line in your .htaccess page.
Now, remember, this is only a workaround. Really, your PHP script should not be exceeding 8 MB, unless your uploading files or doing something else that’s obviously taking up a lot of memory usage. What you should really be doing is trying to figure out why your script is using so much memory and attempt to fix it. One way to figure out how much memory your PHP script is using is to use the memory_get_usage() PHP function. Simply echo it at any point in your script to find out where your memory usage is spiking:
echo memory_get_usage();
If you’re getting this error message in Drupal or Joomla, the likely culprit is a new module or package. For example, in Drupal, the admin/modules page loads every module in your Drupal installation, which can get hairy if a custom module is buggy, corrupt or hacked. Try disabling modules one by one to identify which is bringing the party down. Also, some hosting providers will ignore your attempts to modify the memory limits for your PHP code so you might need to contact your hosting support to assist you. I’ve found sometimes I need to edit the php.ini file and sometimes put the code into the .htaccess file. Either way, hopefully this info here is enough to get you on your way!
