Sending 800k push notifications without loading 800k rows
Chunked reads, a semaphore of two, and one retry pass at the end: the design behind a scheduler that sends 700-800k notifications per run in 6-8 minutes.
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Bulk Push Notification Scheduler
Built the scheduler behind bulk push campaigns: 700–800k notifications per run in 7–8 minutes, read in chunks and sent with controlled parallelism to Android (FCM) and Huawei devices.
700–800knotifications per run
7–8 minto dispatch a full run
how it workshow it works
800k recipients, never all in memory at once
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The problem
A campaign can target 800k or more MSISDNs. Loading that many recipients into memory at once would take the system down, and anything that fails to send still has to go out.
What I built
- Back-office flow: the admin imports a file of MSISDNs and sets the notification's body, type, and send time
- A scheduler picks up unprocessed notifications, then reads the MSISDNs stored against each one
- Recipients are read in fixed-size chunks instead of all at once, since holding 800k+ records in memory is not safe
- A semaphore caps parallelism at 2, so two workers each process a chunk at a time
- Each worker looks up the device (FCM or Huawei) and the notification content, then delivers to the right platform
- Sent records are marked processed, and anything that failed is retried once every chunk has been delivered
Stack.NET, Schedulers, Semaphore, FCM and HMS Push
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