Do PHP static variables persist across Batch API batch items processing?

Question

Do PHP static variables, which do persist during a normal page request, persist between progressive Batch API runs? What about during non-progressive (command-line) batch execution? Does &drupal_static come into play in any way?

In my application, I want to take advantage of in-memory caching across batch processes.

Answer 1

No they do not.

I had a similar question some time ago: https://drupal.stackexchange.com/a/59274/1899

PHP static variables do not persist between requests.

In your batch operation, you receive an array argument as the last argument. Call it &$context (pass by reference), and then you can have persistent variables.

• $context['sandbox'] preserved between iterations of the same batch task. Useful for progressive batch OPs.

• $context['results'] preserved throughout the entire batch progress.

Answer 2

Static variables exist per request, so no, they won't persist across separate batch runs.

If you need to cache data across requests in memory just use redis/memcache/etc, there are contrib modules available for each that hook into the core caching stays so you can use a familiar API