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Date: Mon, 7 Dec 2015 11:24:18 +0100
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To: Netroby <hufeng1987@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=089e013c615082ba7805264c4210
Subject: Re: [PHP-DEV] Why PHP 7 yield from still single thread and blocking thread?
From: me@kelunik.com (Niklas Keller)

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Hi Netroby,


> I wrote a small test. to see if it really concurrent processing any tasks.
> the result looks bad. Still single blocking thread.
>

As the RFC already states:

The actual implementation of coroutine task schedulers is outside the scope
> of this document. This RFC focuses only on the language-level machinery
> needed to make such tools more feasible in userland. It should be obvious
> that simply moving code into a generator function will not somehow make it
> magically concurrent.


You need a task scheduler like Amp (https://github.com/amphp/amp).

With Amp, you code would look like:

<?php
>
> function delayYield() {
>     $delay = mt_rand(1, 5);
>     echo "Delay $delay seconds" . PHP_EOL;
>     yield new Amp\Pause($delay * 1000); // <-- Note: It's not using a
> synchrnous sleep here!
>     return date('Y-m-d H:i:s');
> }
>
> Amp\run(function() {
>
     $promises = [];
>
     for ($i = 0; $i < 3; $i++) {
>           $promises[] = Amp\resolve(delayYield()); // turns the generator
> into a promise so they're combinable with Amp\all
>      }
>
     $dates = yield Amp\all($promises);
>
 });
>

yield from is more to factor larger functions into smaller units than
directly for doing tasks asynchronously.

Regards, Niklas

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