Channel Synchronization in PHP

Our example demonstrates how to use channels to synchronize execution across different processes. In PHP, we’ll use a similar concept with multi-threading, although it’s worth noting that PHP’s threading model is different from Go’s goroutines.

<?php

// This is the function we'll run in a separate thread. The
// $done variable will be used to notify the main thread
// that this function's work is done.
function worker(&$done) {
    echo "working...";
    sleep(1);
    echo "done\n";

    // Set the flag to true to notify that we're done.
    $done = true;
}

// Start a worker thread, giving it a reference to the done flag.
$done = false;
$thread = new Thread('worker');
$thread->start($done);

// Block until we receive a notification from the worker thread.
while (!$done) {
    usleep(100000); // Sleep for 100ms to avoid busy waiting
}

echo "Main thread finished\n";

To run this program, you would save it as channel-synchronization.php and execute it using PHP CLI:

$ php channel-synchronization.php
working...done
Main thread finished

In this PHP version:

1. We define a worker function that simulates some work by sleeping for a second.

2. Instead of using channels, we use a shared boolean variable $done to communicate between threads.

3. We create a new thread using PHP’s Thread class (note that this requires the PHP pthreads extension).

4. The main thread waits in a loop, checking the $done flag until it becomes true.

5. Once the worker thread completes its task, it sets the $done flag to true.

6. The main thread then exits the waiting loop and finishes.

If you removed the waiting loop from this program, it would likely exit before the worker thread even started or completed its work.

It’s important to note that PHP’s threading model is quite different from Go’s goroutines. PHP wasn’t originally designed for concurrent programming, and its threading support (via the pthreads extension) is not as lightweight or as integrated into the language as Go’s goroutines. In many PHP applications, especially web applications, concurrency is often handled at the process level (e.g., multiple PHP-FPM workers) rather than within a single PHP script.