#12813 HIGH 14.1.0: my settings restart may not respond

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#12813: my settings restart may not respond
-------------------------------------+-------------------------------------
            Reporter:  Quozl         |          Owner:  Quozl
                Type:  defect        |         Status:  assigned
            Priority:  high          |      Milestone:  14.1.0
           Component:  sugar         |        Version:  Development build
          Resolution:                |  as of this date
          Blocked By:                |       Keywords:  41002o4
Deployments affected:                |       Blocking:
            Verified:  0             |  Action Needed:  diagnose
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Comment (by Quozl):

 tested with xdotool for repeatability of restart option on menu; test
 passed 780 cycles without any hesitation in restart, so it seems likely
 not to be a problem with session manager or d-bus communication.

 the sugar session manager is coded to ask display clients to save
 themselves, and if there is no response after one second the request is
 repeated, and there is a limit of ten requests.

 the problem can be reproduced by starting xterm from Terminal activity,
 then switching back to the Terminal activity and pressing Ctrl-Z to
 suspend the xterm process, which sends a SIGSTOP to the process.  this
 prevents any save yourself response by xterm, since it cannot receive the
 message and cannot respond.

 as a result, restart is blocked.

 on systems with many running activities, background update processes,
 impaired cooling, or enthusiastic suspend and resume, these may all
 conspire to exceed the ten request limit before all display clients have
 responded, and so the restart will appear to fail.

 next task is to find out what is coded to happen when the limit is
 reached, and either provide an alert, or to ignore the silence and force
 the restart anyway, losing unsaved work.

 related sugar tickets are:
 * https://bugs.sugarlabs.org/ticket/2628 provide feedback when shutdown
 fails, closed by release engineer at the time on the grounds that it was
 not clear what can cause a fail, (now we know better),
 * https://bugs.sugarlabs.org/ticket/3487 restart and shutdown options
 failed, closed because the problem did not reproduce, (now we know better
 that not even logs would have helped),
 * https://bugs.sugarlabs.org/ticket/4345 an activity that cannot quit will
 prevent a restart,
 * https://bugs.sugarlabs.org/ticket/4864 restart from control panel did
 not work, but logs contained an unrelated error.

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Ticket URL: <http://dev.laptop.org/ticket/12813#comment:6>
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