How can PHP be used to create persistent daemons or long-running processes effectively without encountering limitations on function modification at runtime?

When creating persistent daemons or long-running processes in PHP, one common issue is the limitation on function modification at runtime. To overcome this limitation, one approach is to use a combination of signal handling and process forking to create a separate process for the daemon. By forking the process, any modifications made to the parent process will not affect the daemon process, allowing for effective long-running processes without encountering limitations on function modification at runtime.

<?php

// Function to handle signals
function signalHandler($signal) {
    // Handle signals here
}

// Register signal handler
pcntl_signal(SIGTERM, "signalHandler");
pcntl_signal(SIGHUP, "signalHandler");

// Fork the process
$pid = pcntl_fork();

if ($pid == -1) {
    die('Could not fork');
} elseif ($pid) {
    // Parent process
    exit();
} else {
    // Daemon process
    // Code for daemon process goes here
}

// Prevent the main script from exiting
while (true) {
    sleep(1);
}