Bug #1549330 ("dhcpd 4.3.3-5ubuntu7 aborts after getting stuck on futex (bind 9.10 library interaction?)"), which has been marked a duplicate of bug #1551351 is reporting the same symptoms - dhcpd doesn't respond to SIGTERM and appears to be stuck on a futex. I think this is related to the switch from bind 9.9 export library to bind 9.10.
Bug #1549330 ("dhcpd 4.3.3-5ubuntu7 aborts after getting stuck on futex (bind 9.10 library interaction?)"), which has been marked a duplicate of bug #1551351 is reporting the same symptoms - dhcpd doesn't respond to SIGTERM and appears to be stuck on a futex. I think this is related to the switch from bind 9.9 export library to bind 9.10.