Bug 210338

Summary:	mythtv-0.20.2_p14972 - mythbackend segfaults / crashes periodically
Product:	Gentoo Linux	Reporter:	Paul Robson <paul>
Component:	Current packages	Assignee:	Television related Applications in Gentoo's Portage <media-tv>
Status:	RESOLVED NEEDINFO
Severity:	minor
Priority:	High
Version:	unspecified
Hardware:	AMD64
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---

Description Paul Robson 2008-02-16 10:00:57 UTC

I have an AMD64 twin core system and a kernel compiled with SMP on running on x86 Gentoo. mythbackend crashes regularly but with no pattern when running on this system. There appears to be no visible output from this on the cli running mythbackend -d from a terminal or in the log file ; it is only detected when trying to run mythfrontend. There appears to be no way of forcing this, though heavy use of the machine *seems* to make it worse.

This appears to be a problem with mythtv and SMP kernels and reentrant library functions. I had a previous major problem with mythtv-setup which now appears to have been fixed where on an SMP system it was almost impossible to scan the DVB channels because it would crash at some point in the scan, but (again) with no consistency at all. I fixed this by using taskset -c 0 mythtv-setup to start it whereupon it would work perfectly.

A similar fix appears to have worked on my system, by using taskset to lock mythbackend to the single CPU core.

I've added

taskset -p -c 0 `cat /var/run/mythbackend.pid`

immediately after the call to start-stop-daemon in the start() procedure in /etc/init.d/mythbackend ; it has now run faultlessly for about 3 days now (previously it would never run for more than a few hours without crashing)

Reproducible: Always

Steps to Reproduce:
Cannot be forced to occur by user actions, but happens consistently.

Actual Results:
Has produced a stack dump sometimes, but now just seems to stop the mythbackend server. Can always be fixed by restarting mythbackend

Comment 1 Jakub Moc (RETIRED) gentoo-dev

2008-02-16 10:28:01 UTC

Post your emerge --info and attach a backtrace...

http://www.gentoo.org/proj/en/qa/backtraces.xml

Comment 2 Steve Dibb (RETIRED) gentoo-dev

2008-04-25 13:39:10 UTC

NEEDINFO