Ah, thanks for the details there! So, given that my Cloud Functions project is a Go app (and would be the exact same code between Functions and Run), if I were to run that in a very minimal container (something like Alpine), I could get roughly the same cold start time as Cloud Functions, but fewer of them since I can respond to multiple requests using the same instance.
I'll probably do some experimentation on my end as well to test. Any suggestion how long I should wait between tests to ensure a cold start on both Cloud Functions and Cloud Run?
I think you can force cold starts between your tests by re-deploying your function/container. You could (optionally) leave a small buffer (<1 minute) after the deployment to ensure that traffic has fully migrated.
I spoke too soon. The deploy will bring up an instance instead of your first request. To force a cold start, you could set concurrency to '1' and send two concurrent requests. You should see a log entry such as the following when a new instance starts up:
"This request caused a new container instance to be started and may thus take longer and use more CPU than a typical request."
Alternatively, you could set up an endpoint that shuts down the server (which will shut down the instance - not advised for production code).
As an aside, the "K_REVISION" environment variable is set to the current revision. You can log or return this value to test whether traffic has migrated to a new version (instead of waiting a minute).
I'll probably do some experimentation on my end as well to test. Any suggestion how long I should wait between tests to ensure a cold start on both Cloud Functions and Cloud Run?