[mythtv-commits] Ticket #9893: SIGSEGV waking up non-existant threads

[MythTV]

#9893: SIGSEGV waking up non-existant threads
-------------------------------------------------+-------------------------
 Reporter:  Ian Dall <ian@…>                     |           Type:  Bug
   Status:  new                                  |  Report - Crash
Milestone:  unknown                              |       Priority:  minor
  Version:  Unspecified                          |      Component:  MythTV
 Keywords:                                       |  - General
                                                 |       Severity:  medium
                                                 |  Ticket locked:  0
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 Version: v0.25pre-2556-gc12e7d7-dirty

 I am seeing SIGSEGV almost immediately on starting mythbackend. This
 happens often but not always. I haven't been able to figure out the
 circumstances in which this happens. It might be related to the order in
 which threads are run.


  There is no log file, but the console output is:


 2011-07-02 15:43:33.136749 C  mythbackend version: master
 [v0.25pre-2556-gc12e7d7-dirty] www.mythtv.org
 2011-07-02 15:43:33.136925 C  Enabled verbose msgs: important general
 2011-07-02 15:43:33.136988 C  Setting Log Level to LOG_INFO
 2011-07-02 15:43:33.137259 I  Added logging to the console
 2011-07-02 15:43:33.137284 I  Added database logging to table logging
 2011-07-02 15:43:33.162102 C  Setting up SIGHUP handler

 A full backtrace is attached. The SIGSEGV is in thread #4.

 The issue seems to be that MythSystemIOHandler::BuildFDs calls
 readThread->wake with NULL readThread.

 Changing to:
  if (readThread) readThread-wake

 (and likewise for writeThread) seems to work, but maybe only solve the
 symptoms. Perhaps there is a race in thread startup

-- 
Ticket URL: <http://code.mythtv.org/trac/ticket/9893>
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