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In-Reply-To: <E4BE4688-3CD1-4CE8-A818-5A862F0293F5@trowski.com>
Date: Mon, 21 Dec 2020 17:33:33 -0500
Cc: php internals <internals@lists.php.net>
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To: Aaron Piotrowski <aaron@trowski.com>
Subject: Re: [PHP-DEV] [RFC] Fibers
From: mike@newclarity.net (Mike Schinkel)

> On Dec 17, 2020, at 11:30 AM, Aaron Piotrowski <aaron@trowski.com> =
wrote:
>=20
> Hello everyone!
>=20
> I would like to introduce an RFC for adding full-stack fibers to PHP: =
https://wiki.php.net/rfc/fibers
>=20
> Fibers are primarily used to implement green-threads or coroutines for =
asynchronous I/O. Fibers are similar to threads, except fibers exist =
within a single thread and require cooperative scheduling of the fibers =
by the process. Since fibers do not require a full CPU context switch, =
they are lightweight and more performant than multi-processing or =
threading for awaiting I/O.
>=20
> An implementation as an extension is at =
https://github.com/amphp/ext-fiber
>=20
> Fibers are a complex feature. The RFC contains many examples and links =
to code using fibers to help explain and demonstrate what is possible, =
however I=E2=80=99m certain many more questions and concerns will arise. =
Looking forward to feedback and discussion.
>=20

This is interesting, and potentially very useful.

I am curious about how you propose access to shared memory across =
fibers?  What will happen if two fibers try to update a $GLOBALS =
variable at the same time?  Or a property of the same object?  How will =
developers manage that?

-Mike

P.S. Have you considered concurrency functionality like in GoLang[1] =
e.g. channels, where the mantra is "Do not communicate by sharing =
memory; instead, share memory by communicating?"

[1] =
https://medium.com/@thejasbabu/concurrency-in-go-e4a61ec96491#:~:text=3DDo=
%20not%20communicate%20by%20sharing,race%20conditions%2C%20memory%20manage=
ment%20etc.