[RFC] Make OPcache a non-optional part of PHP

Am 27.05.2025 um 18:47 schrieb Ben Ramsey:

Is this really a need, or is it more of a recommendation? If it's left
in a user's configuration, what is the impact?

A warning on startup:

PHP Warning: Failed loading Zend extension 'opcache.so' (tried: ...)

zend_extension=opcache will need to be removed from a user’s php.ini
configuration

Is this really a need, or is it more of a recommendation? If it's left
in a user's configuration, what is the impact?

For people installing PHP from .deb or .rpm sources this shouldn't be an
issue either way as the package managers would take care of that (no more
opcache extension, no opcache.ini).

For the rest, and to avoid a lot of startup warnings we could consider to
explicitly ignore loading of a zend_extension=opcache? Technically this
should be easy but the question is if this is sensible.
People could have an custom extension named opcache.so that does
something else, but that feels very unlikely.

Otherwise, massive fan of the RFC. Having opcache as a given (even if
deactivated) will make it a lot easier to get people to use it and reduce
friction.

Kind Regards,
Volker

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Am 27.05.2025 um 20:07 schrieb Levi Morrison:

To me, being able to turn off opcache defeats the purpose of putting it into
core. In fact, take this part of the RFC's introduction:

Part of this is, at least to me, that "turning off" OpCache is not a
binary things: bytecode caching on/off, bytecode optimization on/off, JIT
on/off, ...

Hi

Am 2025-05-27 20:07, schrieb Levi Morrison:

If opcache can still be disabled, and isn't enabled by default in CLI,
then
in practice we still have all of these issues. The engine may not have
to
care about "is opcache around?" but it still has to care "is opcache
enabled?" Dropping the first part isn't that helpful if the second part
still
has to be asked.

Sebastian's response is quite accurate. While it is true that it will
still be necessary to test the different code-paths, there is no single
thing “OPcache”. It is rather a collection of assorted features that
need to integrate into the engine by hooking into a small number of
hooks (replacing some function pointers). By allowing a tighter
integration with the engine, the OPcache-specific logic can be guarded
by simple if (caching_enabled) or if (optimizer_enabled) statements,
allowing a more direct data flow by means of local variables instead of
being restricted to some kind of “middleware-style” wrapping of the
original logic, possibly duplicating some of it by copy and paste. By
having the entire logic in a single place it also becomes easier to see
if it would be necessary to make some changes to the caching when
modifying the compilation, this is also true for a code reviewer might
be able to point out logic mistakes more easily. And of course in the
future some of the if() statements might also be removed entirely when
it turns out that the logic guarded by them does not have any drawbacks
or the default values of INI settings can be updated.

Long story short: By integrating OPcache directly into the engine, we
can only gain some maintenance flexibility. In the worst case, we are in
no worse situation than currently and it can only get better from there.

And of course there's also the benefits to the users of PHP, since less
configuration will be required for a production set-up. If OPcache is
always loaded, it means that it will also be enabled by default for FPM
set-ups, since opcache.enable defaults to 1.

Best regards
Tim Düsterhus

PS: Did you know that OPcache can optionally replace
(opcache.enable_file_override) the implementation for the
file_exists() function, amongst others? I did not until recently.