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InitPHP FiberLoops — Wiki

Welcome to the official documentation for initphp/fiber-loops — a minimal cooperative task scheduler for PHP, built on native fibers.

It lets you run several tasks on a single thread, hand control back and forth at points you choose, and wait for a sub-task's result — in a few dozen lines of dependency-free code. There is no I/O reactor, no thread pool, no magic: it is a small, sharp scheduling primitive you can read in one sitting and build on.

composer require initphp/fiber-loops

require_once 'vendor/autoload.php';

use InitPHP\FiberLoops\Loop;

$loop = new Loop();

$loop->defer(function () use ($loop) {
    foreach (['a', 'b', 'c'] as $step) {
        echo "task-1: $step\n";
        $loop->next();              // yield: let the other task run
    }
});

$loop->defer(function () use ($loop) {
    foreach (['x', 'y', 'z'] as $step) {
        echo "task-2: $step\n";
        $loop->next();
    }
});

$loop->run();                       // drive every task to completion

task-1: a
task-2: x
task-1: b
task-2: y
task-1: c
task-2: z

The two tasks interleave because each yields with next() after every step. That single idea — cooperative yielding — is the whole library.

What it is (and is not)

It is	It is not
A cooperative scheduler: tasks take turns when they yield	A preemptive one: nothing interrupts a running task
Concurrency on one thread (interleaved progress)	Parallelism (work running on multiple cores)
A primitive you build reactors, pipelines and state machines on	A full async runtime like ReactPHP or Amp
Dependency-free, ~90 lines, PHP 8.1+	An I/O event loop with stream/timer polling

Start here

• New to the package? Read Installation, then Quick Start.
• Want the big picture? Read Core Concepts — how the scheduler actually works.
• Looking for patterns? Jump to Recipes.
• Need the exact contract? See the API Reference.

Use the sidebar to navigate. Every code example on this wiki is a complete, runnable script, and the output shown beneath it is the program's real output.

Requirements

• PHP 8.1+ — fibers are a core language feature since 8.1, so there is nothing else to install.

Links

• GitHub repository
• Packagist package
• Changelog