Channel Scan Crashes at 100%

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marynya
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Channel Scan Crashes at 100%

Post by marynya » Sun Sep 20, 2020 7:04 pm

Fedora 32 Linux
MythTV 31.0 (Fedora repository)
MariaDB 10.4.14
Hauppauge tuner card (PCI)

mythtv-setup channel scan crashes at 100% (after showing channels found) with the following output:

-------------------------------------
2020-09-06 13:30:20.023824 E [8912/9093] SignalMonitor recorders/dvbchannel.cpp:1196:GetSNR DVBChan[1](/dev/dvb/adapter0/frontend0): Getting Frontend signal/noise ratio failed.
eno: Invalid argument (22)

Scan parameters:
Desired Services : tv
Unencrypted Only : yes
Logical Channel Numbers only: yes
Complete scan data required : yes
Full search for old channels: yes
Remove duplicate channels : yes
/usr/include/c++/10/bits/stl_vector.h:1045: std::vector<_Tp, _Alloc>::reference std::vector<_Tp, _Alloc>::operator[](std::vector<_Tp, _Alloc>::size_type) [with _Tp = ChannelInsertInfo; _Alloc = std::allocator<ChannelInsertInfo>; std::vector<_Tp, _Alloc>::reference = ChannelInsertInfo&; std::vector<_Tp, _Alloc>::size_type = long unsigned int]: Assertion '__builtin_expect(__n < this->size(), true)' failed.
Handling Aborted
Aborted (core dumped)
----------------------------------------

This occurs even if I delete mythcoverg and rebuild the configuration from scratch. I assumed this was due to the known MariaDB bug but that is supposed to be fixed in 10.4.14 and everything else appears to be working. I have certain channels which will not lock on "Play TV" and which show no data in the listings. If recorded, no file is created. Other channels are fine, as are optical and file playback. Everything was working until recently. It was about the time some channels changed their format but the MariaDB problem showed up at about the same time. I don't see references to this problem so It is likely something specific to my system but it has eluded me so far.

Any suggestions would be welcome.

Mike

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kmdewaal
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Re: Channel Scan Crashes at 100%

Post by kmdewaal » Sun Sep 20, 2020 9:19 pm

The MariaDB bug is, if memory serves me right, fixed in 10.4.15 but this should not influence mythtv-setup.
That the crash happens at 100% complete might indicate that this caused by option processing which is done after scanning.
You could try doing scans with different options, e.g. "Remove duplicate channels" to no, or "Full search for old channels" to no, and see if that makes a difference.

To investigate what happens I would like to have a full debug log of the complete scan, start this like this:

Code: Select all

mythtv-setup -v channel,chanscan,record,siparser --loglevel=debug
and capture all output. If the (gzipped) file is too big to post here you use e.g. pastebin or wetransfer or gmail to me directly.
I would also like a gdb backtrace. Can you make a backtrace like this:

Code: Select all

gdb mythtv-setup
<do the scan>
gdb> thread apply all bt full
and post that also.

Thanks,
Klaas.

marynya
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Re: Channel Scan Crashes at 100%

Post by marynya » Mon Sep 21, 2020 12:37 am

Klass

I turned all options off and it worked so I put them back one at a time and it appears to be the "Logical Channel Number Required" option which causes the crash. All of the others can be on. I am not entirely sure what that does but leaving it off appears to be an adequate work-around for my purposes. The scan got me all of my channels back. Is this something you would want to look into further, or perhaps I should file a formal bug report. It looks less like something specific to my system.

Thanks for the Help!

Mike

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kmdewaal
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Re: Channel Scan Crashes at 100%

Post by kmdewaal » Mon Sep 21, 2020 5:49 am

Glad that it works for you now and this is definitely a bug in mythtv-setup that needs to be fixed. Please create a bug report (that is in Github nowadays) if possible and attach the log and the traceback.

marynya
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Re: Channel Scan Crashes at 100%

Post by marynya » Mon Sep 21, 2020 6:43 pm

Thanks again for the help and for the instruction in creating the log files. I will see if I can file a useful bug report.

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kmdewaal
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Re: Channel Scan Crashes at 100%

Post by kmdewaal » Wed Sep 23, 2020 7:42 am

I did have a look at the code but I cannot find something obviously wrong. If you can send just the log file and the gdb backtrace that would be great.

Thanks,
Klaas.

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