"It is now possible to configure the number of concurrent requests served by each of your app's dynamic instances.. You can configure Go instances to serve up

"It is now possible to configure the number of concurrent requests served by each of your app's dynamic instances.. You can configure Go instances to serve up to a maximum of 500 concurrent requests. This setting allows your instances to handle more simultaneous requests by taking advantage of Go's efficient handling of concurrency, which should yield better instance utilization and ultimately fewer billable instance hours." AppEngine may or may not decide to spin up another instance before your maximum concurrent requests is reached - but hey, pretty rad that you can do this now. Few hundred requests per instance is not bad at all and this makes the auto scaling less of a black box.