Hi internals, I would like to open the discussion of a new RFC:
https://wiki.php.net/rfc/async_scheduler_abi The proposal gives the engine a coroutine representation and makes the component that drives coroutines, the scheduler, pluggable by an extension. It adds no classes, no functions, no constants and no syntax: the engine compiles in no PHP symbols at all. With no scheduler registered, PHP behaves exactly as it does today. This is not the True Async RFC. It is the minimal engine core extracted from that work: the activation contract, the notifications the engine raises, adoption of fibers onto the scheduler, and per-coroutine storage. Any user-facing API (spawn(), await(), channels) stays in extension space; True Async is one possible provider on top, not the subject of this proposal. The implementation exists, and I am the one contributing it: https://github.com/php/php-src/pull/22561 The PR carries the engine changes plus an in-tree reference scheduler (ext/test_scheduler, disabled by default) that fills every slot from an ordinary extension; the upstream test suites run unchanged and schedulerless in the same binary. A bridge extension that registers a scheduler written in plain PHP exists out of tree, as runtime proof that the seam is sufficient. Points likely of interest for existing code: a scheduler can adopt fibers started by ReactPHP, Revolt or AMPHP, per fiber and declinable; the proposal ships the per-coroutine storage that would later let ob_start() and friends become coroutine-safe; there are no goroutines and no parallelism, everything runs in one OS thread. Feedback is welcome. Regards, Edmond
