There might be times where a task (for example, a Drush command or a PHP script) might take so long to complete that it hits one of PHP's constraints such as memory_limit, max_execution_time, or max_input_vars. In these cases, when you foresee that a task might take a considerable amount of time or resources to complete, it is safer to split the work into chunks that can be completed in smaller, independent, and consecutive processes. This is what Drupal's Batch API (https://www.drupal.org/node/180528) is for. In this section, we will explain how it works and examine how a contributed module uses it in order to complete a large task safely.
The most common errors we might find during a long process are:
Allowed memory size of [some number] bytes exhausted: This means that our script attempted to use more memory than the maximum allowed to PHP at thememory_limitsetting.Fatal error: Maximum execution time of 30 seconds exceeded: This means that our script took...