Comment 5 for bug 1710278

named is being asked to reload its zones quite frequently, sometimes within the same second:
Aug 11 16:31:08 maas named[3174]: received control channel command 'reload'
Aug 11 16:31:17 maas named[3174]: received control channel command 'reload'
Aug 11 16:31:18 maas named[3174]: received control channel command 'reload'
Aug 11 16:31:22 maas named[3174]: received control channel command 'reload'
Aug 11 16:31:26 maas named[3174]: received control channel command 'reload'
Aug 11 16:31:29 maas named[3174]: received control channel command 'reload'
Aug 11 16:31:30 maas named[3174]: received control channel command 'reload'
(...)
Aug 11 17:07:35 maas named[3174]: received control channel command 'reload'
Aug 11 17:07:35 maas named[3174]: received control channel command 'reload'

Eventually it gets stuck:
Aug 11 17:15:16 maas named[3174]: received control channel command 'reload'
Aug 11 17:15:16 maas named[3174]: loading configuration from '/etc/bind/named.conf'
Aug 11 17:15:16 maas named[3174]: reading built-in trusted keys from file '/etc/bind/bind.keys'
<stuck>

An idea to try to reproduce this would be to issue such aggressive reloads on a multi-core machine.