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A comment on AWS Lambda Web Functions. Parent comment

Re:AWS Lambda Web Functions by CharlieDigital on Tuesday October 13, 2026 @03:51PM (#50077634)
When scale to 0, it only bills when actively serving a request. BUT, the instance doesn't go cold immediately; you are only billed while it is serving even if the instance is active.

This diagram helps visualize: https://www.gstatic.com/bricks/image/5eb3c8e9-6159-4e2f-ba98... (gray bar at the top shows when the instance is started and when it ends; blue bars show actual request, and green bars show the billing)

If there's a 10s gap between requests, you are not billed for the 10s gap, but it is still effectively hot; instance does not stop. Request that comes back in 10s later does not have a startup penalty because the instance is still up.

How do you leverage this to build a high throughput system with no cold starts? Just prime it with a short single request (e.g. `/health`) before instance is stopped.

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Re:AWS Lambda Web Functions by rahimnathwani on Tuesday October 13, 2026 @04:12PM (#50077967)
I assumed you were talking about instance-based billing (what I've always used), but I think you're talking about request-based billing?
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Re:AWS Lambda Web Functions by CharlieDigital on Tuesday October 13, 2026 @04:44PM (#50078458)
Request based billing indeed.
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