Performance issue with sending notifications to multiple devices - Suggestion for improvement

[GabrielAziz]

Hi,

I'm experiencing a performance bottleneck when sending notifications to a large number of devices (more than 20 at a time). Our platform allows users to select specific recipients, making device groups and topics unsuitable for this use case.

To address this, I'm considering using Sidekiq to handle the notification sending. However, the current implementation requires instantiating a new FCM client for each job, which leads to unnecessary re-authentication and performance overhead.

I propose the following improvement:

1. Generate the authentication token in the main application service.
2. Pass the token and firebase_project_id to the Sidekiq worker.
3. Instantiate the FCM client within the Sidekiq worker using the provided token and firebase_project_id, instead of passing the full google_credentials again.

This approach would avoid redundant authentication and significantly improve the performance of sending notifications to multiple devices.

Thank you for considering this suggestion.

[cacheflow]

What's the performance bottleneck you're seeing when using Sidekiq as a background job processor? At one job, we've used FCM with Sidekiq to send hundreds of thousands messages per day to devices.

[sabman]

Yea same question as @cacheflow do you know where the time is being spent "re-authentication". In either case in theory this could be added as an alternative way to create an fcm instance I just don't know what the pitfalls are - we might need to have a fallback for when token expires etc.

@GabrielAziz do you have more details on how this could be accomplished - in code or psudocode

[sabman]

related #141 ?