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Re: Ticket #7135: multiple [mythfrontend] <defunct>

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mythtv at cvs

Oct 26, 2009, 2:23 AM

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Re: Ticket #7135: multiple [mythfrontend] <defunct>

mythtv at cvs

Nov 2, 2009, 6:15 PM

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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 5, 2009, 12:33 AM

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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 5, 2009, 10:35 AM

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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 5, 2009, 12:42 PM

Post #5 of 18 (2105 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

#7135: multiple [mythfrontend] <defunct>
---------------------------------------+------------------------------------
Reporter: simons.philippe@… | Owner: ijr
Type: defect | Status: infoneeded_new
Priority: minor | Milestone: unknown
Component: MythTV - General | Version: head
Severity: medium | Mlocked: 0
---------------------------------------+------------------------------------

Comment(by Bill Meek <llibkeem@…>):

Started wondering why I have 13 defuncts and the report before mine and
the original had only 2. So, I plugged in an SD card into my card reader,
restarted the frontend and my defunct count dropped from 13 to 12.

Most of the time, there are no cards plugged into the card reader.

On a roll here, I shutdown and disconnected the USB plug for the card
reader (which has 5 slots CF/SD/uSD...). Restarting the frontend again,
I got '''2''' defuncts, (for /dev/sd0?) which I'm guessing match log
entries:

{{{
MMUnix::AddDevice() Error: failed to stat /dev/bdi,
MMUnix::AddDevice() Error: failed to stat /dev/power,
}}}

When the card reader is plugged in, there are 12 Error entries.
2 each for /dev/sd[defgh] and /dev/sr0.

{{{
bill [at] rc:~/Download$ zcat mlog.gz|cut -c25- |grep /dev/
MMUnix::AddDevice() Error: failed to stat /dev/bdi,
MMUnix::AddDevice() Error: failed to stat /dev/power,
MMUnix::AddDevice() - Added /dev/sdd
MMUnix::AddDevice() Error: failed to stat /dev/bdi,
MMUnix::AddDevice() Error: failed to stat /dev/power,
MMUnix::AddDevice() - Added /dev/sde
MMUnix::AddDevice() Error: failed to stat /dev/bdi,
MMUnix::AddDevice() Error: failed to stat /dev/power,
MMUnix::AddDevice() - Added /dev/sdf
MMUnix::AddDevice() Error: failed to stat /dev/bdi,
MMUnix::AddDevice() Error: failed to stat /dev/power,
MMUnix::AddDevice() - Added /dev/sdg
MMUnix::AddDevice() Error: failed to stat /dev/bdi,
MMUnix::AddDevice() Error: failed to stat /dev/power,
MMUnix::AddDevice() - Added /dev/sdh
MMUnix::AddDevice() Error: failed to stat /dev/bdi,
MMUnix::AddDevice() Error: failed to stat /dev/power,
MMUnix::AddDevice() - Added /dev/sr0

}}}

There are truly no /dev/bdi or /dev/power files, however,

{{{
/sys/devices/pci0000:00/0000:00:14.1/host6/target6:0:0/6:0:0:0/block/sr0/bdi
}}}
exists.

My frontend logs go back as far as 2009-06-16, which is when I started
running
the trunk. The 1st entry with this type of error started on 2009-07-21
and I was
at 20844. I update my box about every 100 commits. The card reader was
purchased
on 2008-11-12 and most likely installed the same day, although I won't
swear to that.

Hope this helps.

Bill

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7135#comment:13>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Nov 6, 2009, 3:45 PM

Post #6 of 18 (2123 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 6, 2009, 3:50 PM

Post #7 of 18 (2106 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 6, 2009, 3:56 PM

Post #8 of 18 (2104 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 6, 2009, 4:46 PM

Post #9 of 18 (2096 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

#7135: multiple [mythfrontend] <defunct>
---------------------------------------+------------------------------------
Reporter: simons.philippe@… | Owner: ijr
Type: defect | Status: infoneeded_new
Priority: minor | Milestone: unknown
Component: MythTV - General | Version: head
Severity: medium | Mlocked: 0
---------------------------------------+------------------------------------
Changes (by mdean):

* status: new => infoneeded_new

Comment:

Attached patch, mythtv-7135-defunct_processes.patch , might work to
prevent the zombie processes. I can't reproduce the issue, so I'm posting
the patch for others to test.

The only way I could get defunct processes with my contrived test
application was to delete the QProcess before the process exited. It's
possible that this can happen when deleteLater() is called right after
kill(), so the patch just puts another waitForFinished() call after the
kill() to allow the process to die before deleteLater() gets called (it
will wait much less than 2s, but will give up after 2s if the kill()
fails). This extra waitForFinished() should probably be done regardless
of whether it solves the issue or not.

However, in theory, if the specified application doesn't exist,
waitForStarted() should return false, meaning that in the described cases,
we should be returning from the waitForStarted() block above. (If you
enable -v important,general,media on mythfrontend, you should see "Error -
udevinfo failed to start!" and/or "Error - udevinfo failed to end!
Terminating" which will indicate whether the problem is in the
waitForStarted() or waitForFinished() block.) If the problem is in the
waitForStarted() block, we may need to do the same kill() and
waitForFinished() in it before deleteLater().

If someone can test and adjust the patch as necessary, please report back
whether it works (and upload any modified version of the patch). #6137
(udevadm vs udevinfo) will be handled separately.

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7135#comment:17>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Nov 7, 2009, 12:09 PM

Post #10 of 18 (2077 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 18, 2009, 7:50 PM

Post #11 of 18 (1928 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 19, 2009, 6:33 AM

Post #12 of 18 (1914 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 19, 2009, 11:24 AM

Post #13 of 18 (1911 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 19, 2009, 12:04 PM

Post #14 of 18 (1910 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 20, 2009, 5:37 PM

Post #15 of 18 (1874 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

#7135: multiple [mythfrontend] <defunct>
---------------------------------------+------------------------------------
Reporter: simons.philippe@… | Owner: ijr
Type: defect | Status: new
Priority: minor | Milestone: unknown
Component: MythTV - General | Version: head
Severity: low | Mlocked: 0
---------------------------------------+------------------------------------

Comment(by Bill Meek <llibkeem@…>):

Update: haven't given up, but the number of defuncts changes. I can't
figure out why.

I usually had about 15 defunct processes. The next patch dropped that to
a solid 5. Both "bdi" and "power" appear on my machine, "trace" was added
because I saw a comment on gossamer-threads by jarpublic. This seems like
a keeper.

{{{
Index: mediamonitor-unix.cpp
===================================================================
--- mediamonitor-unix.cpp (revision 22872)
+++ mediamonitor-unix.cpp (working copy)
@@ -553,7 +553,9 @@

// skip some sysfs dirs that are _not_ sub-partitions
if (*pit == "device" || *pit == "holders" || *pit == "queue"
- || *pit == "slaves" || *pit ==
"subsystem")
+ || *pit == "slaves" || *pit ==
"subsystem"
+ || *pit == "bdi" || *pit == "power"
+ || *pit == "trace")
continue;

found_partitions |= FindPartitions(
}}}

I suspect that mediamonitor-unix.cpp isn't and wasn't causing the actual
defuncts to occur.
When I was at 5, there were a matching 5 failures to mount. That makes
sense, because there are no memory cards plugged in any of the 5 slots.
In these cases, myth_system() is called to do the mounts and I tried the
below. But the number of defuncts now floats between 1 and 6. '''Not'''
recommending this as a fix, but the change does make a difference.

{{{
Index: mythmedia.cpp
===================================================================
--- mythmedia.cpp (revision 22872)
+++ mythmedia.cpp (working copy)
@@ -121,7 +121,7 @@
.arg(m_DevicePath);

VERBOSE(VB_MEDIA, QString("Executing '%1'").arg(MountCommand));
- if (0 == myth_system(MountCommand))
+ if (0 == myth_system(MountCommand,
MYTH_SYSTEM_DONT_BLOCK_PARENT))
{
if (DoMount)
{
}}}

I keep tripping over why is it that udevinfo works and the error case
doesn't? udevinfo returns the same string, although the default has no
trailing new line. I tried appending a new line to the default case,
(ret.append(QChar '\n')) to no avail.

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7135#comment:23>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Nov 21, 2009, 1:38 AM

Post #16 of 18 (1853 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

mythtv at cvs

Nov 22, 2009, 7:08 PM

Post #17 of 18 (1784 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

#7135: multiple [mythfrontend] <defunct>
---------------------------------------+------------------------------------
Reporter: simons.philippe@… | Owner: ijr
Type: defect | Status: new
Priority: trivial | Milestone: unknown
Component: MythTV - General | Version: head
Severity: low | Mlocked: 0
---------------------------------------+------------------------------------

Comment(by Bill Meek <llibkeem@…>):

I added VERBOSE lines to print out the child PIDs in myth_system and found
that they didn't match those of the defunct processes. So I did the same
[udevinfo->pid()] in mediamonitor-unix.cpp right after udevinfo->start and
got an exact match! The usleep() in the following has eliminated the
defuncts for me. The additional tests below that cut down the number of
?unrequired? attempts.

{{{
Index: mediamonitor-unix.cpp
===================================================================
--- mediamonitor-unix.cpp (revision 22889)
+++ mediamonitor-unix.cpp (working copy)
@@ -229,6 +229,8 @@
args << sysfs;
udevinfo->start("udevinfo", args);

+ usleep(100000);
+
if (!udevinfo->waitForStarted(2000 /*ms*/))
{
VERBOSE(VB_MEDIA, msg + ", Error - udevinfo failed to start!");
@@ -553,7 +555,10 @@

// skip some sysfs dirs that are _not_ sub-partitions
if (*pit == "device" || *pit == "holders" || *pit == "queue"
- || *pit == "slaves" || *pit ==
"subsystem")
+ || *pit == "slaves" || *pit ==
"subsystem"
+ || *pit == "bdi" || *pit == "power"
+ || *pit == "trace")
+
continue;

found_partitions |= FindPartitions(
}}}

Of course those affected could just add a shell script something like this
as /sbin/udevinfo:

{{{
# If you already have udevinfo, you don't want this script!!!
UDEVADM=/sbin/udevadm

if [ ! -e $UDEVADM ]; then
echo "Strange, you don't have $UDEVADM either, bye!"
exit 1
fi

RESULT=`$UDEVADM info $1 $2 $3 $4 2>&1`

RETURN_CODE=$?

if [ $RETURN_CODE = 0 ]; then
echo "$RESULT"
else
echo "device not found in database"
fi

exit $RETURN_CODE
}}}

--
Ticket URL: <http://svn.mythtv.org/trac/ticket/7135#comment:25>
MythTV <http://www.mythtv.org/>
MythTV
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mythtv at cvs

Dec 3, 2009, 7:22 PM

Post #18 of 18 (1549 views)
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Re: Ticket #7135: multiple [mythfrontend] <defunct> [In reply to]

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