PHP has apcu as the in-memory cache
And it’s not a joke, PHP is actually the most secure runtime environment out there for web hosting, PRECISELY because of the shared-nothing architecture.
Faster runtimes exist, like Swoole and recently FrankenPHP, to do evented programming like Node JS. But let me tell ya — you risk all kinds of leaks, both of unfreed memory and of secrets, across requests. It ain’t worth it most of the time!
What if you need any kind of in-memory cache? Or in general, any kind of application maintaining state, for, say, performance reasons?