Frontend Instances graph not accurate?

[dloomer]

I have a feeling that others have brought up this same question, but a search for frontend instances brings back so many results and they're difficult to sift through ...

In one of my applications I'm questioning what I see in the "Instances" graph for my frontend.

This app used to do a ton of batch processing in the frontend, and understandably would show 4-8 instances running at either time, both under the Instances link and in the graph. I have since moved almost all of the batch processing to backends, and my Instances link now shows just 1-2 instances, sometimes 3, running at any given time on the frontend (and that is total instances not just active). I check it pretty obsessively, and always see the results I'm hoping for: the backend is taking up the processing with a hard maximum number of instances, while the frontend usage is now very light.

So why is it that my instances graph looks like this? It suggests that I have 3-4 frontend instances at any given time, never dipping below 2 (although I have observed 0-1 running for extended periods, and again that is total instances not just active). Also, why is the "Active" line always showing close to zero? It seems like the Total is overstating and Active is understating my actual usage.

I just made these tweaks a couple days ago, so I've yet to see my first "bill" showing how many frontend instances I would have been billed for under the new pricing model, but I'm afraid it's going to show what I see on the graph rather than what I see under the Instances link.

I have a couple other apps which do very little on the frontend and which always show at most 2 instances running under the Instances link, and for those apps the graph is consistent with what I see elsewhere. It just seems to be this one app (app name: mn-live).

[dloomer]

Let's say in one hour I have six different instances spin up and down, never two running at the same time, and some occasional space in between.

Will that show on the graph as six or <1 instances? And is that what I will be billed for?

Is the Active line computed different from Total, instead measuring the average number of active instances at any moment during that hour, which in my case might in fact be close to zero?