BIND-9.16.1 memory leak?

[sthaug at nethelp.no]

Followup:

> 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.

I now have a pcap file of queries that I can replay with the "drool"
application, and I'm consistently seeing similar memory leak problems
(i.e. the problems are reproducible). The memory leak rate seems to be
very approximately linear with the query rate - so replaying at 10
times the original speed means we also leak around 10 times as much per
minute.

Upgrading to 9.16.2 (and also libuv 1.36.0) makes no difference - the
same memory leak is observed.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no