Found the issue - a use after free in send_response() if I close the session early due to an error. Was continuing to the next bit. Put a temp fix in place, will push a proper one later.
What is it about HN that overwhelms small servers like this? It was a small static page so I wouldn't think it'd be that much load on the server itself, even for an OrangePi like this one.
Too many simultaneous connections for his router maybe? Or too much bandwidth for his internet connection?
If they are behind a NAT/ stateful firewall there is just so much connections it will handle at once. I think OpenWRT has like 16K max by default, f.ex. So for less than 16K requests by different users/IPs… each is kept for about 1 minute I think… it quickly will go down, I guess. :)
With OpenWRT we can increase the limit, if needed. But it's a delicate process you need to balance out carefully depending on your router. I doubled my slots and it works fine:
It's done via /etc/sysctl.conf
> net.netfilter.nf_conntrack_max=32768
Afterwards "sysctl -p" to apply/ reload the config file. But increasing blindly is a bad idea… it needs to be done with ip_conntrack_buckets in sync for proper balance (memory use, CPU usage). Best to read upon it.
But just going from 16K to 32K shouldn't be any problem for most routers these days.