Value for max_accelerated_files inconsistent

[no-one]

https://docs.contao.org/5.x/manual/de/installation/systemvoraussetzungen/ recommends 16000, while https://docs.contao.org/5.x/manual/de/performance/php-setup/ recommends 20000. Do different values really make sense here?

[fritzmg]

/cc @Toflar

The default is 10_000. Should we recommend 16_000 or 20_000?

[no-one]

It seems that neither of these values is a good idea, since neither of them would actually be used (see: https://www.php.net/manual/en/opcache.configuration.php#ini.opcache.max-accelerated-files).
The actual possible values are: 223, 463, 983, 1979, 3907, 7963, 16229, 32531, 65407, 130987, 262237, 524521, 1048793

[Toflar]

The number of files should be

a) counted against your app (not just /vendor but also cache files etc. so it's best to check that regularly.
b) rounded up to the next prime number. Otherwise PHP calculates this automatically (which costs an tiny amount of resources every time the number is fetched)

[no-one]

A relatively simple Contao 5 installation with a few extensions has around 20000 files here. So 32531 would probably be a good value for the manual?

[fritzmg]

You don't have to define the exact prime number. Just choose a value that is suitable for your Contao instance. The internals of how opcache then chooses the actual number are not relevant for you. PHP itself sets a default of 10_000 - which will then actually be 16_229 internally.

In a Contao 5.6 installation with none of the other bundles (i.e. no news, calendar etc.) there will be 14_058 PHP files. With all the bundles it will be 16_379 files. With more installed packages it will be obviously more. One of my customer's instances has 59_085 files.

But only a fraction of those will ever be relevant. For example spatie/schema-org alone has 1843 PHP files - one for each schema.org entity. Most of which you will likely never use. You could check the actual usage with

opcache_get_status()['opcache_statistics']['num_cached_scripts']

In a normal contao/managed-edition this number will be between 6000 to 7000 for the first back end request for example - but that number will obviously grow for every request where new components are used.

Thus overall, for a vanilla Contao instance the default of 10_000 (i.e. 16_229) will likely be enough.