[mythtv-users] Slow deletes were causing backend to hang and/or cause seg faults

Kenan Ezal SBMythTV at cox.net
Sun Jan 4 05:12:00 UTC 2009


This is continuation of the topic found here:

http://mythtv.org/pipermail/mythtv-users/2008-December/242458.html

I thought that a new title would be beneficial to clarify the cause of my problems and maybe help others.

My system information is:
Linux MythTV2 2.6.27.5-41.fc9.x86_64 #1 SMP Thu Nov 13 20:29:07 EST 2008
x86_64 x86_64 x86_64 GNU/Linux
Dual core CPU E2180 @ 2.00GHz with 3.9GiB

My video partition is a RAID 5 with an ext3 filesystem.

I discovered within the last couple of days that the cause of my problems outlined in the original post (backend hanging/seg faults) were due to "slow delete" being turned on. Once I turned slow deletes off my problems went away and my system became stable.

Long story short, I become convinced after logging using the "-v all" option for both the frontend and backend. While I have not looked into the actual code, I gathered from the log that once you mark a program for slow delete it gets placed into a database for in-use files, and then gets taken out and put back into it again (multiple times) for some reason. Then the log just outputs the following sequence forever:

2008-12-30 23:49:54.111 MythEvent: SCHEDULE_CHANGE
2008-12-30 23:49:54.145 write -> 16 45      BACKEND_MESSAGE[]:[]SCHEDULE_CHANGE[]:[]empty
2008-12-30 23:49:54.150 write -> 21 45      BACKEND_MESSAGE[]:[]

I'm suspecting an infinite loop with some condition never being satisfied. Maybe the system is waiting for a confirmation that the slow delete is finished? The file does actually get deleted from my filesystem, however.

I have edited logs if anyone is interested in looking at them. The original log was 370MB (just overnight)!

-Kenan









More information about the mythtv-users mailing list