You are running an application in google app engine that is serving production traffic. you want to deploy a risky but necessary change to the application. it could take down your service if not properly coded. during development of the application, you realized that it can only be properly tested by live user traffic. how should you test the feature?

You need to split the traffic to your test version.

Explanation:

Google app engine has a built-in feature that allows you to split a small fraction of your traffic to your test version.

You can split traffic using an IP address, so when the app receives a request, it can hash the Ip to a value between 0 to 999, and use it to re-route the request.

This way you don't need to stop your service during your tests and also avoid any risk involved with it.