[mythtv] [mythtv-commits] Ticket #1805: Backend not responding, with backtrace and log
spam
spam at sma2.rain.com
Sat May 13 05:25:51 UTC 2006
f-myth-users at media.mit.edu wrote:
> Date: Fri, 12 May 2006 20:47:25 -0700
> From: Jim Westfall <jwestfall at surrealistic.net>
>
> MythTV <mythtv at cvs.mythtv.org> wrote [05.13.06]:
> > #1805: Backend not responding, with backtrace and log
> > -------------------------------------+--------------------------------------
> > Reporter: tom at redpepperracing.com | Owner: ijr
> > Type: defect | Status: new
> > Priority: minor | Milestone:
> > Component: mythtv | Version:
> > Severity: medium |
> > -------------------------------------+--------------------------------------
> > The symptom that I have been experiencing is that the backend will all of
> > a sudden stop responding to connection requests. The process is still
> > running, and it's not eating CPU, but neither a frontend nor mythweb can
> > connect to the backend. I finally managed to get a backtrace and backend
> > log when it happened.
> >
> > Version:
> > root at mythtv:/var/log# mythbackend --version
> > Library API version: 0.19.20060331-1
> > Source code version: 9918
> > Options compiled in:
> > linux debug using_lmsensors using_v4l using_oss using_alsa using_ivtv
> > using_lirc using_x11 using_xv using_xrandr using_frontend using_backend
> >
> > Machine is an AMD Sempron 2200, 512MB RAM, 2xPVR-250.
> >
> > See attached backtrace and backend log from around where it happened. I
> > was experimenting with de-interlace and XvMC settings, so I was going in
> > and out of live tv a number of times just before it happened. Not sure if
> > that is related. It also seems to happen around the turn of the hour when
> > a couple of recordings start. Also of note is that the recordings continue
> > to actually record until I stop and restart the backend process, and
> > resume when it comes up.
> >
>
> I assume you have a slave backend too?
>
> Looking at the backtrace (your master backend?) it appears to have a lock
> on the socket that is waiting for a slave backend to respond about
> generating a pixmap. At the same time the main app thread is trying to
> process a customEvent, which is blocked trying to get the lock on the
> same socket. The main app thread being blocked like this is likely
> causing all qt event processing to stop.
>
> Interesting.
>
> Is this likely to work the same in 18.1? At least once a month,
> I have a similar lockup, in a setup with one MBE and one combined
> FE/SBE. Communication between the FE and the MBE just hangs. At
> the same time, MythWeb stops being able to serve pages (they
> eventually just time out). There hasn't been much of a pattern
> to it, except that I don't think it tends to happen -unless- I'm
> doing UI operations pretty much at the same time. (Obviously,
> this is something of a heisenbug, since I can't -tell- that the
> lockup has happened unless I -am- trying to use the UI... :)
>
> I'm reasonably sure that the MBE continues to be able to continue
> recording in-progress shows, and even starts recording new ones,
> in the hung state (though I'm not 100% sure of this recollection).
> So I wind up having to wait until there's no activity in the
> recordings directory, and then boot the MBE, and -then- I also
> have to boot the FE/SBE, since booting the MBE invariably screws
> up the FE/SBE no matter why I booted the MBE. (E.g., once I boot
> the MBE, the MBE thinks that the SBE's tuners are unavailable and
> won't schedule recordings on them, and sometimes (usually?) the
> FE can't even talk to the database, either, although I may be
> misremembering that latter part. Booting the FE/SBE fixes the
> problem of unavailable tuners; is this behavior still prevalent
> in 19?)
>
> P.S. Unlike the OP, I'm doing absolutely nothing fancy with video;
> my FE is just spitting SD video out the TV-out of a PVR-350. Also,
> my hangs have nothing to do with LiveTV, which I almost never use.
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>
>
> !DSPAM:4465645e265517818312239!
>
I have the same thing but because I have 3 SBE running, the first MBE
restart usually will not pickup any of the SBE tuners. It will list the
names but none of the tuners will show-up. If I restart the MBE again it
will then find one SBE set of tuners (random) and then I have to restart
the other SBE(s) to have the master see it's tuners.
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