Magento 2 – Fix Fatal Error ‘Allowed Memory Size’ During Static Content Deploy

The problem comes from .htaccess. One of the values is php_value memory_limit 256M. This doesn't make sense on the first view, but on the second it is explainable.

I don't know why magento implemented this idiot thing, but what happend is, the following method reads the information from .htaccess and processes them:

\Mage_Shell_Abstract::_applyPhpVariables
protected function _applyPhpVariables()
{
    $htaccess = $this->_getRootPath() . '.htaccess';
    if (file_exists($htaccess)) {
        // parse htaccess file
        $data = file_get_contents($htaccess);
        $matches = array();
        preg_match_all('#^\s+?php_value\s+([a-z_]+)\s+(.+)$#siUm', $data, $matches, PREG_SET_ORDER);
        if ($matches) {
            foreach ($matches as $match) {
                @ini_set($match[1], str_replace("\r", '', $match[2]));
            }
        }
        preg_match_all('#^\s+?php_flag\s+([a-z_]+)\s+(.+)$#siUm', $data, $matches, PREG_SET_ORDER);
        if ($matches) {
            foreach ($matches as $match) {
                @ini_set($match[1], str_replace("\r", '', $match[2]));
            }
        }
    }
}

It's hard to say exactly why that chunk of code is trigging the memory error without more context - a stack trace, description of what actions are ongoing when the error occurs, etc.

But, I can definitely say that by going with a more modern version of PHP you will see decreased memory usage. You could always manually raise the 1GB, but even if you do that you will see more benefit with PHP 5.4 or 5.5. More information on PHP memory here.

What version of Magento are you using? Double check the system requirements here and be sure you meet them all.