PHP memory limit – increase memory allocation

December 7th, 2011 | By: | PHP | No comments »

Sometimes, when executing a script with a strong memory usage, we might reach the PHP memory limit.

Fatal Error

This is what we can see when that moment happens:

Fatal error: Allowed memory size of a certain amount bytes exhausted (tried to allocate another amount bytes) in /path/to/script.php

Configuring php.ini

This means you have exceeded PHP memory limit. The default value is set in php.ini file with the following line:

memory_limit “amount of memory”

To change this you need to open your php.ini file (which can be located in a number of places depending on your system: find where is php.ini) and edit this line.

Example:

memory_limit "512M"

We will now need to restart Apache to allow your modification to take effect.

Setting PHP memory limit with ini_set()

In some cases we will not be able, or do not want to edit our php.ini file. We can also set the limit in a script, with the ini_set function:

ini_set('memory_limit','512M');

NOTE: When dealing with time-consuming operations, PHP might time out when it reaches the time limit. However, other than PHP memory limit, we can also set PHP time limit.