PHP Fatal Error when using W3TC_CONFIG_DATABASE

Hi there,

Since version 2.8.8, the following fatal error is being thrown on sites using the W3TC_CONFIG_DATABASE constant set to “true”:

PHP Fatal error: Allowed memory size of 1073741824 bytes exhausted (tried to allocate 1073741832 bytes) in /var/www/pub/wp-content/plugins/w3-total-cache/ConfigDbStorage.php on line 499

Changing memory_limit does not resolve the issue (tested increasing from 256M to 1024M), which suggests a memory leak somewhere in ConfigDbStorage.php.

A quick glance would suggest a change to the while loop in the query function within this file results in an infinite loop:

2.8.8:

$row = mysqli_fetch_object( $this->result );
while ( false !== $row ) {
	$this->last_result[ $num_rows ] = $row;
	++$num_rows;
	$row = mysqli_fetch_object( $this->result );
}

 2.8.6:

while ( $row = mysqli_fetch_object( $this->result ) ) {
	$this->last_result[$num_rows] = $row;
	$num_rows++;
}

Downgrading back to 2.8.6 resolves this issue. I have not tested 2.8.7. Use of W3TC_CONFIG_DATABASE is required in this instance due to the production environment used.

PHP Version: 8.1

Thanks,

Emmanuel