Describe the implementation and use cases of PHP Fibers for asynchronous programming. How do they compare to traditional threading?

PHP Fibers (introduced in PHP 8.1) enable cooperative multitasking:

Implementation:

$fiber = new Fiber(function (): void {
    $value = Fiber::suspend("Hello");
    echo "Fiber resumed with: " . $value;
});

$result = $fiber->start(); // "Hello"
echo $result;
$fiber->resume("World"); // Outputs: "Fiber resumed with: World"

Use Cases:

• Asynchronous I/O operations
• Non-blocking database queries
• Concurrent HTTP requests
• Event-driven programming
• Implementing async/await patterns

Comparison with Threading:

• Fibers: Cooperative, single-threaded, no race conditions, lower memory overhead
• Threads: Preemptive, multi-threaded, potential race conditions, higher overhead
• Fibers: Explicit suspension points, deterministic execution
• Threads: OS-controlled scheduling, non-deterministic

Advantages: Better performance for I/O-bound operations, easier debugging, no need for locks or synchronization primitives.