dnsdist: Carbon intervals are slightly off when exporting to multiple servers and one is unreachable

[aj-gh]

• Program: dnsdist
• Issue type: Bug report

Short description

When multiple Carbon servers are configured in dnsdist (with multiple "carbonServer" statements) and one is unreachable the reporting frequency to the remaining server(s) becomes unreliable, for example 32 seconds instead of 30 at random intervals, which causes some issues for reports that rely on exact data update intervals.

Environment

• Operating system: Ubuntu 18.04
• Software version: 1.5.2
• Software source: PowerDNS repo (1.5.2-1pdns.bionic)

Steps to reproduce

1. Configure at least two carbonServer's
2. Make one of them unreachable (timeout)
3. Validate reporting frequency to the remaining reachable carbon server

Expected behaviour

Strict reporting interval

Actual behaviour

Random reporting interval +/- a few seconds each..

Other information

"As discussed."
Thanks. 😉