Upcoming Recordings suddenly blank -- Scheduler error?

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paulh
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by paulh »

You could try running the frontend under gdb and when the FE becomes unresponsive switch to gdb and press CTRL-C and get a backtrace. That may give a clue where it is getting stuck.
MSorice
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by MSorice »

Here's what I get from provoking the error under "gdb mythfrontend.real" and then CTRL+C'ing as suggested:

Code: Select all

^C--Type <RET> for more, q to quit, c to continue without paging--

Thread 1 "mythfrontend.re" received signal SIGINT, Interrupt.
0x00007ffff1e50aff in __GI___poll (fds=0x7fff28003cd0, nfds=11, timeout=2)
    at ../sysdeps/unix/sysv/linux/poll.c:29
29      ../sysdeps/unix/sysv/linux/poll.c: No such file or directory.
I'm not sure what this can mean.
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paulh
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by paulh »

You will hopefully get a more useful backtrace if you then type

Code: Select all

thread apply all bt full
MSorice
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by MSorice »

I've attached what that produces.
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gdb-log.txt
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paulh
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by paulh »

Unfortunately the bt doesn't really help since there isn't enough context to show where in the code all those threads are running and which mutexes they are waiting on probably because there are no debug symbols available to generate that information.
m983467
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by m983467 »

I am having similar issues to this, but my general linux skills are not great. I'm trying to enter the mysql command bill6502 recommended above ( SELECT cardid,recpriority FROM capturecard WHERE recpriority != 0 ORDER BY cardid;), but I'm struggling to get into the mythtv database from the terminal.

How do I get into mysql and select the mythtv database so I can run this command?
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paulh
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by paulh »

First of all this problem should already be fixed so you probably just need to upgrade to a new enough version of fixes/31 or master whichever you use and the problem will go way :)

If you still want to know how to run those queries then something like this should work.

If you have a working frontend then on the same machine in a terminal find the config.xml file that will tell you the host, user, password and database name to use. The default location of the config.xml file is in the users home directory under the hidden directory .mythtv so something like this will print it out for you

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cat ~/.mythtv/config.xml
If you don't find it there it may be in the /etc/mythtv directory.

In that file you can find a <Database> section with all the login details required to open a MySQL session to the MythTV database.

Now you can use that info to login to MySQL like this (substitute localhost for your value from <Host>, mythtv is the <UserName> and mythconverg is the <DatabaseName>). When prompted enter the password from <Password>.

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mysql -h localhost -u mythtv -p mythconverg
You can now enter the SQL queries to run making sure to include the final ';' character so MySQL knows that is the end of the query.

When you are done type quit to exit MySQL and return to the commandline prompt.
MSorice
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by MSorice »

paulh wrote:
Mon Nov 22, 2021 7:53 pm
Unfortunately the bt doesn't really help since there isn't enough context to show where in the code all those threads are running and which mutexes they are waiting on probably because there are no debug symbols available to generate that information.
I see. Well, this problem continues and may be getting worse as measured by the proportion of queries that cause hangs. Is there anything else we should try? I considered perhaps recompiling with debugging tokens, but I haven't compiled MythTV from source before.
m983467
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by m983467 »

Thanks for the reply. I am running the fixes/31 version, and my problem is still present, so I guess my issue must be different. Maybe I should start a new thread.

Basically my symptoms are as described here, upcoming recordings shows none even though recording rules do exist, live TV works and records also. One difference in my situation is that if I stop and restart the backend, everything will work normally (upcoming recordings are visible and record normally) for some amount of time, maybe several hours and then it will stop working again.

Any suggestions/recommendations?
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bill6502
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Re: Upcoming Recordings suddenly blank -- Scheduler error?

Post by bill6502 »

@m983467, I agree, new thread. This problem was solved and the commits are released.
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