BIND-9.16.1 memory leak?

[sthaug at nethelp.no]

We have what appears to be a significant memory leak in BIND-9.16.1.

Environment:
 FreeBSD 12.1-STABLE.
 BIND-9.16.1 installed from packages.
 Also uses libuv-1.35.0 installed from packages.
 Authoritative only.
 Around 800 zones of varying sizes. DNSSEC in use.

Running a ps command for the named process every minute and logging
the result, I see the named virtual memory size (VSZ) increasing at
around 1.2 Mbyte/minute, and the resident size (RSS) increasing at
around 0.85 Mbyte/minute. No problems due to this so far, but pretty
obviously it's not viable in the long run.

I tried reading the CHANGES from 9.16.2, and didn't see anything which
suggested a fix for a memory leak problem.

Any suggestions?

Steinar Haug, Nethelp consulting, sthaug at nethelp.no