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I aim to create an application that will be deployed thanks to Google App Engine.

Before that I would like to calculate the cost of Google App Engine.

For this I have to provide the Number of instances, per hour. How can caluculate this number of Instances ?

To reformulate, imagine I have 1 thousand users connected, how many users can 1 instance afford ?

Thank you for your answer and help

Regards

Benoit

Benoit Foussier
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2 Answers2

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It's really hard to answer without more info. App engine consumption will depend on the nature of your app, the average session span and usage hours, how well you optimize your implementation and so much more variables...

Don't think about how many instances, think about how many instance hours you'll need to serve your users if you can figure how much you'll be consuming you could get an estimate using the App engine pricing calculator .

jirungaray
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  • thanks jirungaray. Your answer is consistent with https://cloud.google.com/appengine/docs/adminconsole/performancesettings#Setting_the_Frontend_Instance_Class – Benoit Foussier May 03 '15 at 17:27
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Completely depends on the code that runs on each request. You need to make it more specific to get a better answer. Ive had carefully implemented apps that receives thousands of requests per minute with a single instance. How long each request takes and the memory it consumes is key as well as the frontend instance type you select to use.
Appengine also lets you calibrate some parameters like min/max latency to control when more instances are launched.

Zig Mandel
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  • Thank you for answer Zig. Imagine each request consumes 100Kbytes Memory during 30 seconds, how could I dimension my instance and thus deduce the number on necessary for my 1K connected users ? Are some rules ? For example a maximum Memory ? – Benoit Foussier May 03 '15 at 09:03
  • you need to look at the documentation. You can choose how much memory your instance has available, for example. Of course there are rules. – Paul Collingwood May 03 '15 at 12:22
  • If each request takes 30sec you will need a lot of instances. A well designed app should take milliseconds to respond to a request. – Zig Mandel May 03 '15 at 13:42
  • I updated the answer to mention about latency settings. Look at the docs for that too – Zig Mandel May 03 '15 at 13:54
  • thanks, got it. I found the documentation you mentioned at https://cloud.google.com/appengine/docs/adminconsole/performancesettings#Setting_the_Frontend_Instance_Class The default class for frontends is F1, which gives you 128MB of memory and 600MHz of CPU capacity. – Benoit Foussier May 03 '15 at 17:26