Hi,

I'm a bit confused regarding the issue #23571 where APCu is suggested to be used as adapter for the cache.system key. I am facing around with the same issue ("Cache warmup doesn't warm Symfony\Component\Form\Util\OrderedHashMap") in the prod environment.

This confuses me:

#23571 (comment)

Your issue [...] is related to the cache.system cache pool that is used at runtime

https://symfony.com/doc/current/setup/file_permissions.html

In the prod environment [...], as long as you run php bin/console cache:warmup, no cache files will need to be written to disk at runtime.

APCu and APC are not available, but OPCache is enabled, so the optimized PhpFilesAdapter is used for the cache.system pool which seems okay to me in production.

I also don't understand the problem. All registered services using the cache.system service have its own CacheWarmer implementation, so php bin/console cache:warmup should also warmup the cache.system pool, so no cache files should be written at runtime, or am I wrong?

Thanks in advance for any clarification,
Enrico