PHP 多线程在微服务架构中的作用？

<?php

use Psr\Log\LoggerInterface;
use React\EventLoop\Loop;
use React\Promise\Deferred;
use Swoole\Coroutine\{MultiProcess, Redis};

class RedisClient
{
    private Redis $redis;

    public function __construct()
    {
        $this->redis = new Redis([
            'host' => '127.0.0.1',
            'port' => 6379,
        ]);
    }

    public function get($key): Promise
    {
        $deferred = new Deferred();
        $this->redis->get($key, function (string $result) use ($deferred) {
            $deferred->resolve($result);
        });
        return $deferred->promise();
    }
}

class App
{
    private LoggerInterface $logger;

    public function __construct(LoggerInterface $logger)
    {
        $this->logger = $logger;
    }

    public function run(): void
    {
        $processes = new MultiProcess();
        $redisClients = [];

        for ($i = 0; $i < 10; $i++) {
            $redisClient = new RedisClient();
            $redisClients[] = $redisClient;

            $processes->add(function () use ($i, $redisClient) {
                $value = yield $redisClient->get("key-$i");
                logger->info("Process $i: $value");
            });
        }

        $processes->start();
        Loop::run();
    }
}

$app = new App(LoggerFactory::create('redis-client'));
$app->run();