catz: <defunct> processes then under load & forking

[pettai]

I'm testing the catalog zones branch https://github.com/NLnetLabs/nsd/pull/294

I've been running it on smaller name servers and it works apart from earlier reported issue https://github.com/NLnetLabs/nsd/issues/288.

A new thing I've discovered is that then NSD is put under production load and it forks very frequently due to zone updates, the catalog zones branch of NSD gets processes during the fork-cycles. Example output:

nsd       663232       1  0 10:52 ?        00:00:22 /usr/sbin/nsd -d -P
nsd       663233  663232 81 10:52 ?        00:47:23 /usr/sbin/nsd -d -P
nsd       869581  663233  5 11:51 ?        00:00:00 [nsd: server 1] <defunct>
nsd       869582  663233  5 11:51 ?        00:00:00 [nsd: server 2] <defunct>
nsd       869584  663233  5 11:51 ?        00:00:00 [nsd: server 3] <defunct>
nsd       869585  663233  8 11:51 ?        00:00:00 [nsd: server 4] <defunct>
nsd       869586  663233  6 11:51 ?        00:00:00 [nsd: server 5] <defunct>
nsd       869588  663233  9 11:51 ?        00:00:00 [nsd: server 6] <defunct>
nsd       869589  663233  5 11:51 ?        00:00:00 [nsd: server 7] <defunct>
nsd       869590  663233  5 11:51 ?        00:00:00 [nsd: server 8] <defunct>
nsd       869591  663233  5 11:51 ?        00:00:00 [nsd: server 9] <defunct>
nsd       869592  663233  5 11:51 ?        00:00:00 [nsd: server 10] <defunct>
nsd       869602  663233  5 11:51 ?        00:00:00 [nsd: server 11] <defunct>
nsd       869606  663233 11 11:51 ?        00:00:00 [nsd: server 12] <defunct>
nsd       869607  663233 16 11:51 ?        00:00:00 [nsd: server 13] <defunct>
nsd       869608  663233 10 11:51 ?        00:00:00 [nsd: server 14] <defunct>
nsd       869609  663233 11 11:51 ?        00:00:00 [nsd: server 15] <defunct>
nsd       869610  663233 11 11:51 ?        00:00:00 [nsd: server 16] <defunct>
nsd       869611  663233 11 11:51 ?        00:00:00 [nsd: server 17] <defunct>
nsd       869612  663233 10 11:51 ?        00:00:00 [nsd: server 18] <defunct>
nsd       869613  663233 11 11:51 ?        00:00:00 [nsd: server 19] <defunct>
nsd       869614  663233 11 11:51 ?        00:00:00 [nsd: server 20] <defunct>
nsd       869615  663233 11 11:51 ?        00:00:00 [nsd: server 21] <defunct>
nsd       869616  663233 22 11:51 ?        00:00:00 [nsd: server 22] <defunct>
nsd       869617  663233 10 11:51 ?        00:00:00 [nsd: server 23] <defunct>
nsd       869618  663233 11 11:51 ?        00:00:00 [nsd: server 24] <defunct>
nsd       869619  663233  9 11:51 ?        00:00:00 [nsd: main] <defunct>
nsd       869620  663233  2 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869621  663233  1 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869622  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869623  663233  5 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869624  663233  1 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869625  663233  3 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869626  663233  1 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869627  663233  1 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869628  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869629  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869657  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869671  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869678  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869679  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869680  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869681  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869696  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869699  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869701  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869707  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869710  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869712  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869713  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869714  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869717  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869719  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869720  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869721  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P
nsd       869726  663233  0 11:51 ?        00:00:00 /usr/sbin/nsd -d -P

I can't find any hints in the log then using verbosity 3, but NSD doesn't seem to suffer from an operational POV. It's siblings (name servers) that are running the "regular" branch haven't showed this behavior at all, so I thought it would be good to mention this for the catalog zones developer(s).