What's the best way to send a notification as fast as possible to > 100.000 users?

[ven0ms99]

I have tried the following:

• sending via topic
  Works, but as of late many users complain that they get the notification >7mins after sending it. Including me. Worked for a long time and suddenly notifications got delayed for some reason.
• sending in chunks of 500 to token (Multicast)
  Works and I think it gets faster to users than sending via topic, but it takes forever to send and thus it does take minutes - what I would like to achieve is to get this down to seconds!
  This is what a message looks like:

$not = new stdClass;
        $not->type = "notification";
        $not->link = "https://www.test.com";
        $not->title = "This is a test";
        $not->body = "Sorry, but this is only a test.";

        $topic = "test";

        $notification = NotificationAlias::create(
            $not->title,
            $not->body
        );

$message = CloudMessage::fromArray([
            'priority' => "high",
            'notification' => $notification,
            'data' => (array)json_decode(json_encode($not)),
            'apns' => [
                'headers' => [
                    'apns-priority' => '10',
                ],
                'payload' => [
                    'aps' => [
                        'alert' => [
                            'title' => $not->title,
                            'body' => $not->body
                        ],
                        'sound' => 'default',
                        'mutable-content' => 1,
                        'thread-id' => "topic-" . $topic
                    ],
                ],
            ],
            'android' => [
                'priority' => 'high',
                'notification' => [
                    'default_vibrate_timings' => true,
                    'default_sound' => true,
                    'notification_priority' => 'PRIORITY_HIGH'
                ],
            ],
        ]);

I can't emphasize enough how crucial it is for my application that users get the notification immediately. I'd be very grateful for any hints.

[jeromegamez]

I think that topic messaging is the most efficient way to do it at the moment - especially since you said that this worked for the longest time and only suddenly got delayed by a lot. It happened before that notifications were delayed and it usually worked itself out after some time. I'd recommend contacting Firebase Support directly to investigate if they know about a current service degradation.

The SDK doesn't support async requests (I thought about: how about sending the chunked batch request in parallel), but I'm pretty sure that Firebase would rate-limit them - the 500 chunk size has certainly been set for a reason 😅

[ven0ms99]

Thank you! The problem is that the official advise is kind of confusing:

Topic messages are optimized for throughput rather than latency. For fast, secure delivery to single devices or small groups of devices, target messages to registration tokens, not topics.

So on the one hand topics are slow and on the other hand tokens shouldn't be used for larger groups.

edit: I'd really like to try sending the request in parallel, but I'm actually unsure how to approach that using PHP.