Backend Hours Count

Question

I use instances of AppEngine Backend, and the daily free quota is 9 instances of hours. However, I use Backend with 10 instances for 16-17 minutes, and my use has already crossed 66%.

The calculation that I had in mind was 17 minutes * 10 copies = 170 minutes ~ 2.8 hours, which, of course, is less than 66% of 9 hours.

Can someone explain to me the billing scheme here?

Answer 1

From https://developers.google.com/appengine/docs/quotas#Requests :

Clock Instance (Paid) In general, the use of an instance is billed on an hourly basis based on the uptime of the instance. Payment begins when the instance starts and ends fifteen minutes after the instance is closed down. You will be billed only for idle instances up to the number of maximum idle instances set on the Performance Settings tab of the Admin Console. Runtime overhead is counted against instance memory.

In your case, you will have 17 minutes of activity + 15 minutes after activity = 32 minutes. So 320 minutes (32 * 10) is pretty close to 2/3 of 9 hours.

You should see the details in the usage history of your application.