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Date: Mon, 27 Oct 2025 19:53:33 +0200
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Subject: Re: [PHP-DEV] Re: PHP True Async RFC Stage 4
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
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From: edmond.ht@gmail.com (Edmond Dantes)

> I am not sure how feasible this is, but would there be a way to split the=
 "async toggle" of IO operations off to its own PR/RFC?
> To me, that is by far the most important part of this RFC as that's the b=
iggest blocker for wider async adoption,
> but I'm not sure how many layers are needed above it to make it possible =
to toggle in a safe fashion.

Ah, I think I understand what you mean.
Yes, from an implementation standpoint, non-blocking behavior is
provided by the Scheduler API and Reactor API. These two APIs are
always available anywhere =E2=80=94 in the core, extensions, and so on.

However, this isn=E2=80=99t part of the RFC itself, as it belongs to
implementation details. Moreover, do you remember the first version of
the RFC? It had a function that explicitly started the Scheduler. So
indeed, in that first version PHP could be in two states: synchronous
and asynchronous.

What=E2=80=99s the difference in this RFC?
PHP is **always** in an asynchronous state. Even when executing
index.php, you can think of it as running inside a coroutine. There=E2=80=
=99s
just a single coroutine, so no switching occurs (although an extension
could, for example, create another coroutine =E2=80=94 which is perfectly
valid).

You keep writing your code exactly as before. You don=E2=80=99t need to thi=
nk
about PHP being =E2=80=9Casynchronous=E2=80=9D now. As long as you=E2=80=99=
re writing code
inside a single coroutine, you=E2=80=99re still writing synchronous code.

-- Ed