Scenario: large Drupal 7 site where cache is extremely slow or fails to clear…
drush cc all
…and eventually PHP runs out of memory (“cannot allocate”).
Check Drush is using the correct version of PHP, it may not be – use
drush status or, more simply:
$ which drush /Applications/DevDesktop/tools/drush $ vim /Applications/DevDesktop/tools/drush # edit the PHP version: [ -z "$PHP_ID" ] && PHP_ID=php7_1