[mythtv-commits] Ticket #5268: mythtv-backend seems to go into endless loop, pegs cpu

[MythTV]

#5268: mythtv-backend seems to go into endless loop, pegs cpu
-----------------------------------+----------------------------------------
 Reporter:  eharris at puremagic.com  |       Owner:  ijr       
     Type:  defect                 |      Status:  new       
 Priority:  major                  |   Milestone:  unknown   
Component:  mythtv                 |     Version:  0.21-fixes
 Severity:  medium                 |     Mlocked:  0         
-----------------------------------+----------------------------------------
 For some reason I haven't been able to narrow down yet, mythtv-backend
 sometimes seems to go into a fairly hard loop and peg the cpu until it is
 restarted.

 The backend still seems to be servicing other requests, as frontends using
 it seem to be able to operate, but are slower apparently due to the load
 on the backend.

 As an additional piece of info, this backend currently has no encoder
 cards in it, it is merely a storage backend for players, so I'm not sure
 why it appears to be continually calling for a reschedule.

 Here's a small snippet of output of "strace -s 64 -t" of the backend
 process in this state:

 {{{
 14:38:19 write(14, "45
 BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty", 53) = 53
 14:38:19 select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
 14:38:19 ioctl(14, FIONREAD, [0])       = 0
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(19, "45
 BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty", 53) = 53
 14:38:19 select(20, [19], NULL, NULL, {0, 0}) = 0 (Timeout)
 14:38:19 ioctl(19, FIONREAD, [0])       = 0
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(14, "45
 BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty", 53) = 53
 14:38:19 select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
 14:38:19 ioctl(14, FIONREAD, [0])       = 0
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(19, "45
 BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty", 53) = 53
 14:38:19 select(20, [19], NULL, NULL, {0, 0}) = 0 (Timeout)
 14:38:19 ioctl(19, FIONREAD, [0])       = 0
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(14, "45
 BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty", 53) = 53
 14:38:19 select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
 14:38:19 ioctl(14, FIONREAD, [0])       = 0
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(19, "45
 BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty", 53) = 53
 14:38:19 select(20, [19], NULL, NULL, {0, 0}) = 0 (Timeout)
 14:38:19 ioctl(19, FIONREAD, [0])       = 0
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(14, "45
 BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty", 53) = 53
 14:38:19 select(15, [14], NULL, NULL, {0, 0}) = 0 (Timeout)
 14:38:19 ioctl(14, FIONREAD, [0])       = 0
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(19, "45
 BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty", 53) = 53
 14:38:19 select(20, [19], NULL, NULL, {0, 0}) = 0 (Timeout)
 14:38:19 ioctl(19, FIONREAD, [0])       = 0
 14:38:19 write(13, "0", 1)              = 1
 14:38:19 write(13, "0", 1)              = 1
 }}}

 Here's version info:
 {{{
 MythTV Version   : 16473M
 MythTV Branch    : branches/release-0-21-fixes
 Library API      : 0.21.20080304-1
 Network Protocol : 40
 Options compiled in:
  linux release using_oss using_alsa using_arts using_jack using_backend
 using_dbox2 using_directfb using_dvb using_firewire using_frontend
 using_hdhomerun using_iptv using_ivtv using_joystick_menu using_lirc
 using_opengl_vsync using_v4l using_x11 using_xrandr using_xv using_xvmc
 using_xvmcw using_xvmc_vld using_bindings_perl using_bindings_python
 using_opengl using_ffmpeg_threads using_libavc_5_3 using_live
 }}}

-- 
Ticket URL: <http://svn.mythtv.org/trac/ticket/5268>
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