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

Michael T. Dean mtdean at thirdcontact.com
Wed Jul 29 02:07:37 UTC 2009


On 07/28/2009 09:24 PM, MythTV wrote:
> #5268: mythtv-backend seems to go into endless loop, pegs cpu
>
>
> Comment(by eharris):
>
>  In case it is helpful, I've narrowed down what seems to be the cause of
>  the problem.  Whenever the backend actually deletes a recording due to the
>  backend getting below the minimum free space limit, shortly thereafter the
>  system goes into the highly loaded continuous issuance of SCHEDULE_CHANGE
>  messages.  Just to be clear, this is NOT caused when a program is marked
>  as deleted, only after the video file is actually deleted.  One additional
>  nuance is that while the load increases significantly (until being "fixed"
>  by restarting the backend) with a single recording being deleted, it
>  usually takes two deletions (on my system) before the load goes high
>  enough to be user-visible and cause problems (video skips, delayed
>  responsiveness, etc).  Three or more deletions usually makes the system
>  practically unresponsive, so the load generating effect seems to be
>  cumulative.
>
>  I can't tell for sure from trac or the changelog, but has this fix made it
>  into the 0.21-fixes branch?  If so, I will upgrade my system to a later
>  version that includes the fix to see if it resolves the issue I am seeing.
>   

The specific changes committed in [18792] (which prompted closure of 
#5268) and described at 
http://svn.mythtv.org/trac/ticket/5268#comment:10 fix code that does not 
exist in 0.21-fixes.  Therefore, the "fix" hasn't made it into 
0.21-fixes, but then again, neither did the bug.  :)

As Anduin mentioned, he didn't find the issue originally reported in 
#5268, so that may well be code that was added at any time in the past.

However, I'm running a 0.21-fixes system and have never seen the 
problem.  Therefore, if this is an issue on 0.21-fixes, it's likely a 
very rare issue that requires some specific MythTV or system 
configuration, so it's not often seen.  That does mean that it's most 
likely to be fixed by someone who can actually observe the issue.

My recommendation is to make sure you have the most current 0.21-fixes 
revision you can get from your packager (assuming you're using packages) 
and see if you still notice issues.  If so, please try to get a 
backtrace ( http://www.mythtv.org/wiki/Debugging --and feel free to fill 
out the section on debugging with packages for your distro once you 
figure out how to install those debug packages :).

Since Myth isn't crashing, you'll need to Ctrl-C to interrupt Myth to 
get the backtrace.  Please make sure you have debugging symbols 
installed and that you use the proper gdb command to get a full backtrace.

Thanks,
Mike


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