The Basic Anatomy of a Fiber
The beauty of PHP Fibers is in their simplicity. Here’s how to create a fiber and get it up and running:

$fiber = new Fiber(function() {
  echo "Fiber started…\n";
  Fiber::suspend(); // Pause the fiber
  echo "Fiber resumed…\n";
});
echo "Fiber starting…\n";
$fiber->start(); // Start the fiber
echo "Main script running…\n";
$fiber->resume(); // Resume the fiber

https://byteblog.medium.com/php-fibers-how-php-is-finally-warming-up-to-asynchronous-programming-39da4d21b8e7
https://itsimiro.medium.com/understanding-fibers-in-php-a-new-way-to-handle-concurrency-ed07424320ff