[dnsdist] dnsdist[]: While reading a TCP question: accepting new connection on socket: Too many open files

[Fredrik Pettai]

Hi,

One dnsdist instance recently got overloaded, and the message (subject + below) appeared a lot in the logs:

	“dnsdist[]: While reading a TCP question: accepting new connection on socket: Too many open files"

Is this only related to too much DNS-traffic over TCP, or could lots of DNS traffic over UDP also potentially lead to slowdown/locking issues for dnsdist TCP handling?

I’ve increased the amount of addLocal() + newServer() workers to be able to handle more traffic.
Dnsdist currently gets 16k fd’s (via systemctl's dnsdist.service configuration)

# grep -E '^Max open files' /proc/$(pidof dnsdist)/limits
Max open files            16384                16384                files

Would it be okay to increase this 4x or so?

What other things could one do to increase dnsdist ability to handle large bursts of DNS traffic better?

Thanks,
/P








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