Curious how this would have compared to a static pmtiles file being read directly by maplibre. I’ve had good luck with virtually equal latency to served tiles when consuming pmtiles via range requests on Bunnycdn.

Well, “bandwidth is expensive” is a true claim, but it's also a very different claim from “a [normal] caching server couldn't handle 56 Gbit/sec”…?

It really depends on the size of the active set. If it fits into RAM of whatever server you are using, then it's not a problem at all, even with completely off-the-shelf hardware and software. Slap two 40gig NICs in it, install Varnish or whatever and you're good to go. (This is, of course, assuming that you have someone willing to pay for the bandwidth out to your users!)

If you need to go to disk to serve large parts of it, it's a different beast. But then again, Netflix was doing 800gig already three years ago (in large part from disk) and they are handicapping themselves by choosing an OS where they need to do significant amounts of the scaling work themselves.

> We are talking about an insane amount of data here. It was 56 Gbit/s. This is not something a "caching server" could handle.

You are not talking about an insane amount of data if it's 56 Gbit/s. Of course a caching server could handle that.

Source: Has written servers that saturated 40gig (with TLS) on an old quadcore.

The tiles need to be rendered. Yes frequent tiles can be cached but you already have a cache… it’s Cloudflare. Theoretically you could port the tileserver to Cloudflare pages but then you’d need to… port it… and it probably wouldn’t be cheaper

One thing that might work for you is to actually make the empty tile file, and hard link it everywhere it needs to be. Then you don't need to special case it at runtime, but instead at generation time.

NVMe disks are incredibly fast and 1k rps is not a lot (IIRC my n100 seems to be capable of ~40k if not for the 1 Gbit NIC bottlenecking). I'd try benchmarking without the tuning options you've got. Like do you actually get 40k concurrent connections from cloudflare? If you have connections to your upstream kept alive (so no constant slow starts), ideally you have numCores workers and they each do one thing at a time, and that's enough to max out your NIC. You only add concurrency if latency prevents you from maxing bandwidth.

Since the limit you ran into was number of open files could you just raise that limit? I get blocking the spammy traffic but theoretically could you have handled more if that limit was upped?

Is it always/only 'laziness' (derogatory, i know) when caching isn't implemented by a site like wplace.live ? Why wouldn't they save openfreemap all the traffic when a caching server on their side presumably could serve tiles almost as fast or faster than openfreemap?