BIND 10 #3074: kea6 fails to start after repeated start/stop

[BIND 10 Development]

#3074: kea6 fails to start after repeated start/stop
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            Reporter:  wlodekwencel  |                        Owner:
                Type:  defect        |  UnAssigned
            Priority:  very high     |                       Status:
           Component:  bind-ctl      |  reviewing
            Keywords:  kea6 config   |                    Milestone:
           Sensitive:  0             |  Sprint-20131015
         Sub-Project:  DHCP          |                   Resolution:
Estimated Difficulty:  0             |                 CVSS Scoring:
         Total Hours:  0             |              Defect Severity:  High
                                     |  Feature Depending on Ticket:
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
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Changes (by muks):

 * owner:  muks => UnAssigned
 * status:  assigned => reviewing


Comment:

 `trac3074` is now ready for review.

 The problem was that Init has two sockets open to msgq subscribed to the
 Init group (it has to start a first socket to track process startup) and
 it does not read from both of them. So msgq keeps queuing data on the
 unread socket (from its side), and after a while, times out and closes the
 socket. However, Init uses this socket still to communicate to msgq, so
 when the socket is closed from the other side (resulting in EPIPE)
 everything collapses. The fix was simple: we unsubscribe from the Init
 group on the unmonitored socket so that nothing is queued up on it from
 the msgq side.

 While debugging this problem, quite a bit of additional logging was
 necessary, but I've only committed the ones that are absolutely essential
 as otherwise the amount of trace logging will hinder performance.

 Some changes were suggested (and made locally) to the DHCP lettuce ticket
 #3140. It seems these have now been made in `trac3140`, so these patches
 have been dropped.

 DHCP team have tried this patch and have found it to fix the issue.

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Ticket URL: <http://bind10.isc.org/ticket/3074#comment:6>
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