[Documentation] Document limitations of using the CompiledContainer

[holtkamp]

Context While step-by-step increasing the use of PHP-DI in a monolithic application, the amount of PHP-DI Definitions also increased. As a result: enabling container compilation involved an increasingly bigger compiled container. In this case the compiled container is a .php file:

• with ~38k lines of code
• which contains a const METHOD_MAPPING array with ~3.5k entries and the same amount of protected function statements
• with a filesize of ~1.9MB
• which uses ~3.9MB of memory according to OpCache

Observation I noticed that this increased size of the compiled container has a negative effect on the performance. "Probably" because on each request the compiled container has to be loaded completely, while only a small part of it is actually used: a nature of a monolithic application: a lot is possible, but a single request only invokes a part of the functionality.

Suggestion It might be good to add a kind of "disclaimer" to the documentation, that it might be good to check whether container compilation actually contributes to better performance and there might be a certain "size" of use of PHP-DI when compiling the container would not be recommended...

Used system:

• PHP 7.1.21
• OpCache 7.1.21
• APCu: 5.1.8

[mnapoli]

:+1:

It might be also interesting to checkout how Symfony handles those situations, maybe they split the dumped container across several files 🤔