I need to clear apcu cache. - first try drush cache rebuild: drush cr
First, try drush cr to rebuild all the caches. It's rare that you actually need to clear APCu cache separately.
APCu is a very small cache, usually 32M, and it's just for the PHP Caches that were previously a part of APC, and are now User Cache see https://www.php.net/manual/en/book.apcu.php for more information.
- Place a script you can call via HTTP that calls
- Request it twice in the web browser following the process outlined in https://www.drupal.org/node/2752961
Each time, you will need to specify the instance to load on each request by adding a
ah_app_server=ded-20746 or `ah_app_server=ded-20747cookie.
Example code of the PHP
<?php echo "APC-User cache: " . apcu_clear_cache ( ). "\n";
This function always returns true. It's a little confusing.
This can also be helpful to monitor and tune APCu cache https://anavarre.net/how-to-monitor-and-tune-apcu/