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

diff --git a/pdns/dnsdistdist/dnsdist.service.in b/pdns/dnsdistdist/dnsdist.service.in
index c7e1b4246aea45d5d5911cb3fc0749c5a2a16009..14e37856cd3e6d7cd6ef525f4224ed6458a08ed2 100644 (file)
--- a/pdns/dnsdistdist/dnsdist.service.in
+++ b/pdns/dnsdistdist/dnsdist.service.in
@@ -22,7 +22,8 @@ NoNewPrivileges=true
 ProtectSystem=full
 ProtectHome=true
 RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
-LimitNOFILE=4096
+LimitNOFILE=16384
+TasksMax=1024
 
 [Install]
 WantedBy=multi-user.target