Assuming the debug symbols I grabbed[1] for my install of bind9 on Xenial match yours (I have bind9 version 1:9.10.3.dfsg.P4-8ubuntu1.7 installed per "apt-cache policy bind9"), I did the following to grab a traceback:
$ sudo apt-get install bind9-dbgsym libdns162-dbgsym libisc160-dbgsym $ gdb /usr/sbin/named core (gdb) set pagination off (gdb) thread apply all bt ... [2] ... Looking at the backtrace in [2], the interesting parts to me are threads 8, 11 and 20, which are possibly involved in a deadlock[3]. Looks like one of the threads is reloading the configuration (something we would expect MAAS to do), and the other is calling dns_resolver_shutdown() via view_flushanddetach(). [1]: https://wiki.ubuntu.com/Debug%20Symbol%20Packages [2]: http://paste.ubuntu.com/25292729/ [3]: Thread 8 (Thread 0x7f95226aa700 (LWP 3203)): #0 __lll_lock_wait () at ../sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135 #1 0x00007f952a351efe in __GI___pthread_mutex_lock (mutex=mutex@entry=0x7f94d4014fe8) at ../nptl/pthread_mutex_lock.c:135 #2 0x00007f952b7a0794 in dns_view_weakdetach (viewp=viewp@entry=0x7f9504389780) at ../../../lib/dns/view.c:597 #3 0x00007f952b7993de in destroy (val=0x7f9504389750) at ../../../lib/dns/validator.c:3891 #4 0x00007f952b79927b in dns_validator_destroy (validatorp=validatorp@entry=0x7f9519462628) at ../../../lib/dns/validator.c:3915 #5 0x00007f952b76b9d1 in validated (task=<optimized out>, event=0x7f95194625d0) at ../../../lib/dns/resolver.c:4722 #6 0x00007f952a9a6360 in dispatch (manager=0x7f952be3b010) at ../../../lib/isc/task.c:1130 #7 run (uap=0x7f952be3b010) at ../../../lib/isc/task.c:1302 #8 0x00007f952a34f6ba in start_thread (arg=0x7f95226aa700) at pthread_create.c:333 #9 0x00007f9529a993dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 Thread 11 (Thread 0x7f9520ea7700 (LWP 3206)): #0 pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185 #1 0x00007f952a9a516b in isc__task_beginexclusive (task0=<optimized out>) at ../../../lib/isc/task.c:1717 #2 0x0000557c34997dc1 in load_configuration (filename=<optimized out>, server=server@entry=0x7f952be44010, first_time=first_time@entry=isc_boolean_false) at ../../../bin/named/server.c:5651 #3 0x0000557c3499a826 in loadconfig (server=0x7f952be44010) at ../../../bin/named/server.c:7162 #4 0x0000557c3499ad48 in reload (server=0x7f952be44010) at ../../../bin/named/server.c:7183 #5 ns_server_reloadcommand (server=0x7f952be44010, args=args@entry=0x7f94fc120af0 "reload", text=text@entry=0x7f9520ea6590) at ../../../bin/named/server.c:7416 #6 0x0000557c34975db5 in ns_control_docommand (message=<optimized out>, text=text@entry=0x7f9520ea6590) at ../../../bin/named/control.c:102 #7 0x0000557c34978b97 in control_recvmessage (task=0x7f952be51010, event=<optimized out>) at ../../../bin/named/controlconf.c:458 #8 0x00007f952a9a6360 in dispatch (manager=0x7f952be3b010) at ../../../lib/isc/task.c:1130 #9 run (uap=0x7f952be3b010) at ../../../lib/isc/task.c:1302 #10 0x00007f952a34f6ba in start_thread (arg=0x7f9520ea7700) at pthread_create.c:333 #11 0x00007f9529a993dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 Thread 20 (Thread 0x7f951c69e700 (LWP 3215)): #0 __lll_lock_wait () at ../sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135 #1 0x00007f952a351efe in __GI___pthread_mutex_lock (mutex=0x7f94d43429f8) at ../nptl/pthread_mutex_lock.c:135 #2 0x00007f952b7642a7 in dns_resolver_shutdown (res=0x7f952be56690) at ../../../lib/dns/resolver.c:9035 #3 0x00007f952b7a06a1 in view_flushanddetach (viewp=viewp@entry=0x7f94fc02cc30, flush=flush@entry=isc_boolean_false) at ../../../lib/dns/view.c:508 #4 0x00007f952b7a0757 in dns_view_detach (viewp=viewp@entry=0x7f94fc02cc30) at ../../../lib/dns/view.c:557 #5 0x0000557c3496e55b in ns_client_endrequest (client=0x7f94fc02cbe0) at ../../../bin/named/client.c:694 #6 exit_check (client=0x7f94fc02cbe0) at ../../../bin/named/client.c:382 #7 0x0000557c34970150 in ns_client_detach (clientp=clientp@entry=0x7f951c69ce18) at ../../../bin/named/client.c:2833 #8 0x0000557c34989ee2 in query_find (client=0x0, event=0x0, event@entry=0x7f9518a862b0, qtype=<optimized out>, qtype@entry=0) at ../../../bin/named/query.c:8328 #9 0x0000557c349921cf in query_resume (task=<optimized out>, event=0x7f9518a862b0) at ../../../bin/named/query.c:3826 #10 0x00007f952a9a6360 in dispatch (manager=0x7f952be3b010) at ../../../lib/isc/task.c:1130 #11 run (uap=0x7f952be3b010) at ../../../lib/isc/task.c:1302 #12 0x00007f952a34f6ba in start_thread (arg=0x7f951c69e700) at pthread_create.c:333 #13 0x00007f9529a993dd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 ** Also affects: bind Importance: Undecided Status: New ** Also affects: bind9 (Ubuntu) Importance: Undecided Status: New ** Changed in: maas Status: New => Triaged ** Changed in: maas Importance: Undecided => Critical -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1710278 Title: [2.3a1] named stuck on reload, DNS broken To manage notifications about this bug go to: https://bugs.launchpad.net/bind/+bug/1710278/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
