I have a Drupal 7 site which requires flushing the cache from time to time. The problem is that whenever I flush the cache (~30 seconds) the site is non-responsive until the flush is over.
What could be the cause and how do I debug this? Thanks
Using a MySQL frontend like phpMyAdmin run
SHOW PROCESSLIST while your site is locked from the cache clear. That should show what is causing the issues for you. My guess is it will be a metadata lock. https://www.drupal.org/project/apdqc was built to prevent db locks in database caused by the cache.