Public bug reported: Software version:
* Description: Ubuntu 12.04.1 LTS * arch : x86_64 * ntp 1:4.2.6.p3+dfsg-1ubuntu3.1 * libc6 2.15-0ubuntu10.2 We hit a strang behavious on some machine, where ntp refuse to quit if stopped right after startup: When running the following command: /etc/init.d/ntp start && /etc/init.d/ntp stop ntp still running and ignoring further kill. In syslog we can see the stop is effectivly taken in account: Oct 8 12:45:36 app01 ntpd[16713]: ntpd exiting on signal 15 Sending more "kill 16713" do nothing. We have the "start and just after stop" behavious on our server, because of https://bugs.launchpad.net/nova/+bug/887162. Short summary: dhcp server don't reply until dhcp client lost the IP and request new IP using broadcast request: * (AFAIK) when dhcp don't get answer from DHCP and remove the IP is call a hook which restart ntp (/etc/dhcp/dhclient-exit-hooks.d/ntp) * dhcp retry just after to grab a new IP and get the IP. Interface goes up, a hook restart one more the ntpd (/etc/network/if-up.d/ntpdate) After digging further, I reproduced the issue on my local machine by using a simple script which start and kill ntpd until we reach the issue. Once the issue reproduced I attached gdb to the process and showed stack (see gdb-stack-dbg.txt). Looking to this stack, it seems that the issue is syslog function which is not re-entrant. When signal SIGTERM occure while "main thread" called syslog, this cause a deadlock. I also attached gdb-stack.txt using packaged ntpd (so no debuging symbol for ntpd function). And I attached ntpd_loop.py : the basic script which start and kill ntpd until it hang. You may need to change the short sleep between start/stop and/or run other resource consuming process on other terminal (I usually do a find /). ** Affects: ntp (Ubuntu) Importance: Undecided Status: New ** Attachment added: "gdb "info stack" during deadlock (with debuging symbols)" https://bugs.launchpad.net/bugs/1063806/+attachment/3386608/+files/gdb-stack-dbg.txt -- You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to ntp in Ubuntu. https://bugs.launchpad.net/bugs/1063806 Title: ntp deadlock while exiting and never stop To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ntp/+bug/1063806/+subscriptions -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs
