如何实现PHP后端功能开发中的异步任务处理？

$pid = pcntl_fork();
if ($pid == -1) {
    // 创建子进程失败
    exit("Error: unable to fork
");
} elseif ($pid == 0) {
    // 子进程中执行任务
    // ... 执行耗时操作
    exit();
} else {
    // 父进程中继续执行其他任务
    // ...
}

// 发送消息到消息队列
$connection = new AMQPConnection($host, $port, $user, $pass, $vhost);
$channel = $connection->channel();
$channel->queue_declare($queueName, false, false, false, false);
$message = new AMQPMessage('task data');
$channel->basic_publish($message, '', $queueName);
$channel->close();
$connection->close();

// 消费消息队列中的任务
$connection = new AMQPConnection($host, $port, $user, $pass, $vhost);
$channel = $connection->channel();
$channel->queue_declare($queueName, false, false, false, false);
$channel->basic_consume($queueName, '', false, false, false, false, function ($message) {
    // 处理任务
    // ... 执行耗时操作
    $message->delivery_info['channel']->basic_ack($message->delivery_info['delivery_tag']);
});
while (count($channel->callbacks)) {
    $channel->wait();
}
$channel->close();
$connection->close();

// 异步任务处理
swoole_async::exec('command', function ($result, $status) {
    // 处理任务结果
    // ...
});

// 协程并发处理
go(function () {
    // 异步任务1
    $result1 = co::exec('command1');

    // 异步任务2
    $result2 = co::exec('command2');

    // 处理任务结果
    // ...
});