CODEWITHSUNDEEP
google-app-engine
minou
minou

Reputation: 16563

Keeping GAE at a single instance with flexibility to scale

I have a relatively low traffic app that can easily be handled by a single instance more than 95% of the time. Occasionally, having more than one instance running would be helpful to provide a better user experience.

It seems that GAE should be able to automatically scale in this way, but I can't get GAE to keep only a single instance when traffic is low. This is what I have tried:

With this configuration, GAE will just about always run two instances even though one is sufficient.

I know I can set max instances to one, but I want to be able to automatically scale when I need it.

Is it possible to do what I want?

Upvotes: 0

Views: 480

Answers (1)

Mihail Russu
Mihail Russu

Reputation: 2536

Note that the min/max property that you are setting are for IDLE instances.

  • Set min instances to 1 means that you will ALWAYS have at least one instance running, even when there are no requests for over 15 minutes. This could be set to 0 if you have low traffic AND your app launches quickly, i.e. under 1-2 seconds, otherwise the users will have bad experience with very slow response on their first request.

  • Set max instances to 3 means that it's OK for GAE to keep up to three instances running at any time, even when there are only few requests. This could be set to 1 to save some costs but would make some requests slow (time it takes to start new instance + time to launch your app) when traffic increases.

The max-idle-instances does not limit the number of instances in the event of a traffic spike, your app will always scale and new instances will keep launching if needed. The min/max settings are only there to help handle a sudden increase in traffic and there is no way to limit the number of instances that can be launched.

Take a look at this article for some more details: Setting the Number of Idle Instances

Regarding your question, you could try decreasing the max-idle-instances to 1 and see if that helps. You don't have to worry about scaling, new instances will still launch if needed, just keep in mind that the experience might not be as smooth for your users. If you decreased the number of max-idle-isntances and you still see more than 1 instance running on very low traffic, then your app might need to be optimized and multi-threading might need to be enabled if it wasn't.

Upvotes: 3

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