mythbuntu-bugs team mailing list archive

[Ludvik Tesar <760319@xxxxxxxxxxxxxxxxxx>]

Public bug reported:

This is bug-report, that includes the solution. I had to spend a lot of
time to solve it and I would like to save a time of other people solving
it.

I am using mythbuntu 10.10, separate mythbackend and mythfrontend
machines. Recently (after about 3 months using mythbuntu), I started to
have problems with failed recordings.

These were the symptoms : Some of scheduled recordings were not
recorded. (About 10% - 50% of all scheduled recordings). In spite of the
fact, that the program was already in the past, detail in mythfrontend
and listings mythweb were saying : "The program will be recorded". I was
not able to force it to record and mythbackend was not willing to admit,
that programs in the past are impossible to record. There was no problem
with conflicts. If there was a conflict, mythtv would tell it. There was
nothing in /var/log/mythtv/mythbackend.log, The log didn't even mention
that it would try to record anything at the particular time. The only
thing were some strange messages concerning database connection, but
they were not co-incident with planned recording start. E.g. the message
about unsuccessful initialization of UPnP due to database connection.
Also, occasionally I had problems with LiveTV not starting, even though
it was possible to start recording and watch it. Usually the problems
vanished, after I restarted the mythbackend machine, but they reappeared
very soon.

My opinion about the reason of problems : I found out that there was no
problem with mysql configuration but with the timing of the start of it.
When mythbackend was starting, the mysql was not yet finished with its
startup. Consequently mythbackend gived up to start some of its
components. That was typically UPnP and other time also other things.
Upon every restart, probably different set of services given up to
start. It is apparent from mythbackend logs (Deleting UPnP client...,
Failed to init MythContext, exiting...) From mysql logs I could find out
the exact moment of starting of mysql, which was possible to compare
with start of mythbackend and it was apparent that until the start of
mysql, the log of mythbackend is full of database connection errors and
failed services and after start of mysql, everything seems to be ok in
the log (but not everything is working). In my opinion, with months of
usage, as the mysql database have grown, the startup sequence was longer
and longer, and at some point it started to interfere with startup of
mythbackend.

The bug is easily reproducible at any installation. if you start mysql
at exactly the same time as mythbackend, you should get similar results.


The solution : I added this :

pre-start script
  sleep 5 # wait for mysql to start
end script

into the file /etc/init/mythtv-backend.conf and all problems are over.
Every recording I planned since then, was recorded.

Recommendation : I think it is the problem of mythbuntu distribution
rather than mythtv itself. It allows to start database after mythbackend
which should not happen. I recommend to add some detection of mysql
database comming up (e.g. through /var/run/mysqld/mysqld.sock) into
/etc/init/mythtv-backend.conf. Many mythtv forums say, that mythbackend
waits for mysql to start, but this assumption is definitely wrong or it
is perhaps disabled in default configuration of mythtv 0.23.1 or in
mythbuntu 10.10.

** Affects: mythbuntu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/760319

Title:
  Programs failed to record with no trace in the mythbackend.log

Status in Mythbuntu, Ubuntu derivative focused upon MythTV:
  New

Bug description:
  This is bug-report, that includes the solution. I had to spend a lot
  of time to solve it and I would like to save a time of other people
  solving it.

  I am using mythbuntu 10.10, separate mythbackend and mythfrontend
  machines. Recently (after about 3 months using mythbuntu), I started
  to have problems with failed recordings.

  These were the symptoms : Some of scheduled recordings were not
  recorded. (About 10% - 50% of all scheduled recordings). In spite of
  the fact, that the program was already in the past, detail in
  mythfrontend and listings mythweb were saying : "The program will be
  recorded". I was not able to force it to record and mythbackend was
  not willing to admit, that programs in the past are impossible to
  record. There was no problem with conflicts. If there was a conflict,
  mythtv would tell it. There was nothing in
  /var/log/mythtv/mythbackend.log, The log didn't even mention that it
  would try to record anything at the particular time. The only thing
  were some strange messages concerning database connection, but they
  were not co-incident with planned recording start. E.g. the message
  about unsuccessful initialization of UPnP due to database connection.
  Also, occasionally I had problems with LiveTV not starting, even
  though it was possible to start recording and watch it. Usually the
  problems vanished, after I restarted the mythbackend machine, but they
  reappeared very soon.

  My opinion about the reason of problems : I found out that there was
  no problem with mysql configuration but with the timing of the start
  of it. When mythbackend was starting, the mysql was not yet finished
  with its startup. Consequently mythbackend gived up to start some of
  its components. That was typically UPnP and other time also other
  things. Upon every restart, probably different set of services given
  up to start. It is apparent from mythbackend logs (Deleting UPnP
  client..., Failed to init MythContext, exiting...) From mysql logs I
  could find out the exact moment of starting of mysql, which was
  possible to compare with start of mythbackend and it was apparent that
  until the start of mysql, the log of mythbackend is full of database
  connection errors and failed services and after start of mysql,
  everything seems to be ok in the log (but not everything is working).
  In my opinion, with months of usage, as the mysql database have grown,
  the startup sequence was longer and longer, and at some point it
  started to interfere with startup of mythbackend.

  The bug is easily reproducible at any installation. if you start mysql
  at exactly the same time as mythbackend, you should get similar
  results.

  
  The solution : I added this :

  pre-start script
    sleep 5 # wait for mysql to start
  end script

  into the file /etc/init/mythtv-backend.conf and all problems are over.
  Every recording I planned since then, was recorded.

  Recommendation : I think it is the problem of mythbuntu distribution
  rather than mythtv itself. It allows to start database after
  mythbackend which should not happen. I recommend to add some detection
  of mysql database comming up (e.g. through
  /var/run/mysqld/mysqld.sock) into  /etc/init/mythtv-backend.conf. Many
  mythtv forums say, that mythbackend waits for mysql to start, but this
  assumption is definitely wrong or it is perhaps disabled in default
  configuration of mythtv 0.23.1 or in mythbuntu 10.10.