Tuning unit file for medium sized setups

Tuning unit file for medium sized setups

We would propose to introduce the TasksMax setting in the unit file. The default value of 512 seems too low, at least for our setup. In addition, if present in the unit file, people will be aware of it.

LimitNOFILE seems also a little bit low.

Our setup consists of 8 DNS backend servers. Each Server with 5 IPv4 and 5 IPv6 addresses. That means dnsdist has to deal with 80 backends. For this setup TasksMax=512 (default) was too low and dnsdist stopped working correctly. We saw many of these messages:

Error creating a TCP thread: Resource temporarily unavailable
Had an error accepting new webserver connection: Resource temporarily unavailable