AIUI, Lambda operates on requests. (Either "calls" to a function, i.e., just invoking a lambda function w/ args and getting the result over the network somewhere else, or as an HTTP handler or a CloudWatch handler, but those are really specialized cases of the first.) Using time.NewTicker/time.After strikes me as something you would do to maintain some sort of background process, which Lambda is not intended for: IIRC, Lambda can arbitrarily freeze your process b/c no requests are being served presently, and that "capacity" isn't needed as far as AWS is concerned. I think under the hood they're doing a cgroup freezer or something, but the result would be exactly what you see: timers firing way too late. They wouldn't fire until the underlying container is unfrozen. This wouldn't be a bug in Go or Lambda; Lambda is specifically designed to do this, so as to free you from needing to care about how much capacity you require¹. (At the cost of making stuff like background timers not work; that's not its model.)

See: https://aws.amazon.com/blogs/compute/container-reuse-in-lamb...

¹ish. take that statement w/ a grain of salt.