Auto clear Autoptimize cache before it gets too large

Autoptimize “makes optimizing your site really easy. It can aggregate, minify and cache scripts and styles, injects CSS in the page head by default (but can also defer), moves and defers scripts to the footer and minifies HTML”, thank you to the plugin authors they have done a great job in making this plugin available and free for everyone. The plugin is almost perfect but doesn’t offer a proper schedule purging mechanism. On this post you will find two different approaches to tackle this “issue”.

The code snippet below added to your theme functions .php will limit the Autoptimize cache to 256MB. Thank you to @rahulpragma to make the below snippet available


# Automatically clear autoptimizeCache if it goes beyond 256MB
if ( class_exists( 'autoptimizeCache' ) ) {
    $myMaxSize = 256000; # You may change this value to lower like 100000 for 100MB if you have limited server space
    $cacheSize=round( $statArr[1]/1024 );
    if ( $cacheSize>$myMaxSize ) {
       header( "Refresh:0" ); # Refresh the page so that autoptimize can create new cache files and it does breaks the page after clearall.

The code snippet below added to your theme functions .php will schedule Cron job to delete the cache every week and month. This code snippet is a bit different from the above this code only cleans up the cache, it doesn’t limit the size of it.

namespace wppress;
class GarbageCollection {
    public function __construct() {
        add_filter( 'cron_schedules', function ( $schedules ) {
            $schedules['weekly'] = array(
                'interval' => 604800,
                'display'  => __( 'Once a Week' ),
            $schedules['monthly'] = array(
                'interval' => 2635200,
                'display'  => __( 'Once a month' ),
            return $schedules;
        if ( ! wp_next_scheduled( 'wppress/garbage/clear') ) {
            wp_schedule_event(time(), 'monthly', 'wppress/garbage/clear' );
        add_action( 'wppress/garbage/clear', [ &$this, 'clear'] );
    public function clear()
        if ( class_exists( '\autoptimizeCache' ) ) {
            /* Clear autoptimize cache once a month */
new GarbageCollection();



I am a Freelance Web Developer and WordPress Expert based in London with a wealth of website development and support experience. I am great at problem solving and developing quick solutions.



    July 13 2018 / 12:23 pm

    This is not working.
    I have tried this on my site.

      Nuno Morais Sarmento

      July 20 2018 / 10:44 am

      Hi there,

      Thank you for passing by on my website and for trying to use my code snippet. What is the log output of your cronjob?


    September 28 2018 / 8:51 am

    Do you know if this would clear all the caches on a multisite network if Autoptimize is active network-wide or just the primary site?

      Nuno Morais Sarmento

      September 28 2018 / 9:37 am

      Hi Tony, thank you for your comment and for passing by on my website. You can pack this code snippet into a plugin and activate the plugin network-wide. Let me know if you need help to do that.


    October 6 2018 / 3:07 pm

    Where should I post the code. Htaccess?

      Nuno Morais Sarmento

      October 7 2018 / 1:25 pm

      Hi Dan, thank you for passing by on my website. The code should be added in your theme functions .php/

    çıplak yazar

    December 12 2019 / 7:39 am

    Thank you so much. I was lookıng for this code.


    December 18 2019 / 6:48 pm

    This is great, thank you – exactly what I needed. Nowhere in the Autoptimize documentation was there anything about autoptimizeCache::clearall(); function… I was under the impression there was no way to trigger the cache clear other than through wp-admin or via some janky workaround that are smattered all over the net. Appreciate it!

      Nuno Morais Sarmento

      December 19 2019 / 9:50 am

      I’m glad I was able to help you 🙂


    January 22 2020 / 10:31 pm

    Hi. Thank you for the first code. But i still have a question: how to clear all cache of “WP Super Cache” plugin too?

      Nuno Morais Sarmento

      January 23 2020 / 5:24 pm

      Hi, you need to go to your Wp-admin area and click Settings under Settings click WP Super Cache –> Contents –> Delete Cache


        January 23 2020 / 7:14 pm

        I mean programmatically. By php code in functions.php file.

          Nuno Morais Sarmento

          January 24 2020 / 9:38 am

          This may help you –

    Riccardo Luigi

    April 3 2020 / 9:15 pm

    Hi Nuno,
    first of all thanks for the snippets.

    However I’m a little bit confused about the second one: you say to put it in functions.php but the tags “” at the end suggest it should be copied into a stand-alone php file.

    What’s the right thing to do?

      Nuno Morais Sarmento

      April 3 2020 / 9:31 pm

      Hi Riccardo,

      Thank you for passing by on my website. Yes, you right, is misleading people. Thank you for that the code is now amended.


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