knotify4 going crazy & breeding like rabbits (+ linguistic discussion of the role of "greetings")

[gene heskett]

On Wednesday, February 22, 2012 01:16:28 AM Duncan did opine:

> gene heskett posted on Mon, 20 Feb 2012 20:29:31 -0500 as excerpted:
> > On Monday, February 20, 2012 08:08:28 PM Chuck Burns did opine:
> >> On 2/20/2012 5:00 PM, gene heskett wrote:
> >> > Greetings;
> 
> ... and salutations! =:^)
> 
> (Completely OT I know, but while I understand the role of greetings IRL,
> at least in part, from the newcomer to signal the event and focus
> attention on the his arrival (among other things, serving notice that
> intended private conversations may need to stop temporarily), I never
> quite understood the role on lists, newsgroups, forums and the like,
> where one presumably /knows/ when one starts a new message or thread,
> and that doing so signals the same functional type of "context switch"
> that "greetings" does IRL.  As such, for lists, newsgroups and the
> like, I'm accustomed to simply starting my question/answer/whatever, no
> greeting or similar redundancies.  I know a lot of others do likewise,
> while others include it as they would IRL or in formal non-electronic
> written correspondence.  But at times I've simultaneously wondered
> bemusedly at a "Hi", "Greetings", etc, opening, and whether my omission
> thereof inadvertently causes mild offense.  This is obviously one of
> those times...
> 
> The wictionary entry for "greeting" notes that it's less common in
> email, etc, as well.  So... why /do/ you (plural "you", addressed to
> anyone who wishes to respond) include such an opening in electronic
> messages such as lists, email and news messages?  Have you even ever
> thought about it before?  Do you get offended if others don't as well? 
> Are these questions just really strange and off the wall, making me
> look crazy? "Inquiring minds want to know!" =:^)
> 
> >> > I have so far today, killed around 75 copies of /usr/bin/knotify4
> >> > which is pegging out all 4 cores of my phenom, and running it up to
> >> > 70C+.
> >> > 
> >> > Killing all copies (which is puzzling because killall can't find
> >> > them but htop can) cleans the system up&  brings back normal
> >> > operation.
> 
> Which killall form did you use?  Quoting the killall (1) manpage:
> 
> 
> killall  sends  a signal to all processes running any of the specified
> commands[.]  If the command name is not regular expression (option -r)
> and contains a slash (/), processes executing that particular file will
> be selected for killing, independent of their name.
> <<<<<
> 
> Note that kde uses a special launcher, kdeinit4, to launch many of its
> "core" programs.  The commandline for these will be kdeinit4 <appname>
> <app-parameters>.  The reasoning is that this allows more efficient
> shared-objects loading, so faster launching and more efficient memory
> usage.
> 
> I'm not sure that's exactly what's going on here (my single knotify4
> instance appears to be a direct child of init, pid 1, and it doesn't
> appear with the kdeinit4 prefixed on its command line), but it is indeed
> quite possible for applications to be launched such that the name and
> the command-line don't match, such that a killall without -r or / won't
> see it.
> 
> As mentioned in the manpage quote above, the absolute executable file
> path (detected by the presence of a / in the name) or a regular
> expression (using -r) can be used instead.  It's possible these would
> get the ones a standard killall misses.
> 
> Of course, the other possibility is that killall sends the signal, but
> the process ignores it, especially if the process is hung.  The default
> SIGTERM (-15) would allow this.  SIGHUP/-1, SIGINT/-2, SIGSEGV/-11, and
> finally SIGKILL/-9, in order of increasing severity, can be used
> instead, with SIGKILL being "kill with predjudice", that is, don't give
> the app a chance to clean up or to say no, just kill it.  Of course,
> this last one can leave half-written files and the like around.  The
> kernel will close them and return memory resources to the system, but
> if it was a config file or the like, it could cause problems at the
> next start, so SIGKILL/-9 should always be used as a last resort.
> 
> Of course signal types is pretty basic Unix, so you probably knew that
> bit, but others reading might not.
> 
> But if killall found at least one process to deliver the signal to, it
> returns success whether or not the process actually responded, while if
> it didn't find a process at all, it returns failure status and complains
> to STDERR, and it's likely that complaint that you were indicating with
> the "killall can't find them" bit.  Just covering the bases, in case...
> 
> >> > But in half an hour I am back to 4 to 6 copies and a pegged cpu.
> >> > 
> >> > This seems to go along with an uptime of 10 days or more, currently
> >> > at 18 days.
> 
> It's likely that few enough people run kde for that long at a time, so
> bugs aren't as likely to be reported.  I happen to run git kernels here,
> and even the kernel merge window (during which I don't normally rebuild
> and test new kernels, just in case there's a crazy "eats filesystems" or
> "eats md/raids" bug during that time, that presumably I'd know about by
> a few days after the merge window closes if I decide to bisect
> something) is only two weeks, so 18 days is likely at the long end for
> no-reboots, here, at least on my main machine.  (My netbook can go much
> longer, but it can spend a month or six weeks in suspend-to-disk
> hibernation, too; it's not like it's actually /running/ more than
> perhaps 24 hours of that.)
> 
> On Linux, that's not an excuse.  On Linux, if it can't handle at least
> six months uptime, it's considered seriously bugged, and rightfully so.
> However, it /is/ a fact.  Long uptime bugs simply won't get as much
> reporting, as fewer people see them, simple as that.
> 
> >> > Is there a permanent fix for this other than switching to (I'd
> >> > rather just have somebody shoot me) gnome or even (quite a bit
> >> > better IMO) xfce?
> >> 
> >> I hate to sound like a smartass..
> > 
> > Not at all.
> > 
> >> but have you tried logging out of kde,
> >> and back in? Your uptime won't suffer, and KDE will be able to
> >> completely refresh.. There may some sort of leak somewhere..
> > 
> > I suspect there is, but running it down seems nearly impossible when
> > it doesn't show up for 2 weeks.
> > 
> >> AFAIK, no one has reported a bug about this.. perhaps if you have
> >> time, you can try to narrow it down to exactly what.
> 
> See what I said above about long-uptime-bugs.  If it's possible to do
> something with it... the whole kde ecosystem should thank you, because
> good bug reporting is rare enough, and good bug reporting of long uptime
> bugs even rarer, but getting them fixed helps stability even for shorter
> uptime people, so it's a good thing... where it's at all possible, of
> course.
> 
> >> You can also try disabling all notifications.. ymmv
> > 
> > I do use inotifywait
> 
> Entirely different kind of notification! =;^)
> 
> Inotify and similar "file event" notifications are often what kernel and
> sometimes app developers mean when they talk about notifications.  They
> notify an APP (not the user, tho the app could potentially notify the
> user if appropriate) about file accesses, changes, etc.  At a similar
> level, udev notifies apps such as kde's device notifier (which in turn
> notifies the user if appropriate) when devices appear or disappear, etc.
> 
> knotify4, OTOH, deals entirely with user-level-app-to-user event
> notifications for things like mail delivery, media changes in the media
> player, keyboard shift-level changes, etc.  These "user notifications"
> are most often either sound events or popup dialogs (now often handled
> by the notifier icon in the systray, tho I'm not sure all such dialogs
> are handled that way yet), but can also involve marking/flashing a
> taskbar entry, logging the event to a file, or running some other
> command.
> 
> It's generally that first one, playing a sound, that causes problems, on
> systems where either the sound system isn't properly configured or where
> it otherwise isn't entirely reliable.  This is almost CERTAINLY what's
> happening in your case.
> 
> > I note that I found another copy of it the 2nd time I went on
> > a killing rampage today, about 75 processes down from the top, killed
> > it too, and the problem has not come back, but something has called
> > up 2 copies of it since I nuked them all.
> > 
> > If that had a visible link to whatever restarts it, that would help
> > considerably in tracking this down, but apparently no one knows what
> > (re)starts it.
> 
> knotify4 is part of kde's internals.  Any time an event occurs that's
> configured to play a sound, popup a notice window, etc, knotify should
> respond with the appropriate action.  But as I said, sound in particular
> can be somewhat problematic.  If the sound doesn't play as knotify is
> configured to play it, that instance of knotify will hang, waiting for
> the event to finish, and at the next such event, kde (kded, maybe? I'm
> not sure exactly which component; maybe it's invoked by the triggering
> app directly, using a library that's part of kdelibs and thus available
> to any kde app?) will find no responding knotify4 and thus will spawn
> another one.
> 
> But if the one is hung waiting on a resource lock it can't get
> (typically it can't open the sound device), and the next one needs it
> too, guess what, the next one gets in line behind the first.
> 
> Lather, rinse, repeat.
> 
> When you notice and start killing all of them, once you kill the one
> that was originally hung (probably one of the oldest, or as you
> mention, one without a lot of CPU time, as it was hung, while the
> others were CPU-poll spinning, waiting on the resource to become
> available), the kernel releases that resource with the killing of the
> hung process, pulling the plug on the waiting queue of all the others,
> thus draining it.
> 
> And since the problem with the sound device that actually hung the
> original knotify4 often has something to do with it suspending after an
> idle timeout, or with something grabbing the sound device exclusively
> (some hardware can cope with multiple streams, some not, thus the use of
> sound servers or alsa's software stream mixer device, dstream or some
> such, I think it's called), but in some cases an app will apparently
> still try to do an exclusive lock on an otherwise sharable device), thus
> triggering the original problem when the original knotify4 tried to
> access the sound device, by the time the original locked-up knotify4 is
> killed, the intermittent problem has generally gone away, so pulling the
> plug allows all those spawned knotify4s to do their thing one right
> after the other, without the problem reoccurring immediately.
> 
> But then later on, when the sound device suspends or something else
> grabs exclusive access again, the whole thing is setup for another
> go-round.
> 
> > But:
> > [root at coyote eagle]# lsof |grep knotify4|wc -l 1198
> > 
> > How the heck can you separate the wheat from the chaff in a list that
> > long..  :(
> 
> FWIW, 1317 here, and to my knowledge, everything's working fine, here,
> just one pid listed for all those, etc.  So 1000+ open files for knotify
> would seem to be normal.
> 
> > Half of that is vlc linked:
> > [root at coyote eagle]# lsof |grep knotify4|grep vlc|wc -l 604
> > 
> > And I haven't specifically used vlc that I know of in months, so I
> > assume a news site I have visited must have called it up.
> 
> Taking a look thru the 1317 listed files, it seems that most of them are
> *.so shared-objects aka libraries with FD=mem, TYPE=REG.
> 
> That many of those shared-objects are vlc related is almost certainly
> due to your use of the phonon-vlc backend -- phonon is how kde handles
> sound, and if it's configured to use the phonon-vlc backend, with all
> the plugins that vlc has, and the fact that knotify4 is responsible for
> kde's sound effects...
> 
> FWIW, 699 appear to be vlc related, here.
> 
> Then there's the other usual X and kde libraries in the list...
> 
> Try this, the grep -v excludes any line with "lib":
> 
> lsof | grep knotify4 | grep -v lib | wc -l
> 
> FWIW, 87, here.  That look a bit more reasonable? =:^)
lsof | grep knotify4 | grep -v lib | wc -l
66

> There's the current working directory (FD=cwd, TYPE=DIR), the root
> directory (FD=rtd, TYPE=DIR, NAME=/), the executable itself (FD=txt,
> TYPE=REG), several memory-mapped font resources (it's an X app, after
> all)
> 
> Then there's the various filedescriptors (FD=0r 1w 2w... etc,
> filedescriptor, read/write/u=both, TYPE=CHR/REG/0000/FIFO/unix/netlink,
> character-device, regular file, unknown/(anon-inode),
> first-in-first-out, unix socket, netlink socket, respectively).  It's
> interesting to note that STDIN is
> /dev/null and STDOUT and STDERR are mapped to $HOME/.xsession-errors, as
> might be expected for an X app.  15 (numbered 0-14) filedescriptors are
> open in this way.  Other than the first three STD*, the rest are various
> fifos, pipes, anon-inodes, unix sockets, etc.  Of interest are FD=8r,
> the kde system config cache (ksycoca4) regular file, FD=9u, netlink
> KOBJECT_UEVENT, and FD=13r, the /dev/urandom character-device.
> 
> Here, the same set (same pid for all) is listed three times, once
> without a "task ID" following the PID, and once each for two different
> task-IDs. I don't have much of a clue what task-id is. (??)
> 
> But it's worth noting that it's the same PID and the same set of open
> files, three times.  87/3=29.  29 actual non-library files... listed
> three times each.
> 
> If the same applies to the 1317, I didn't rigorously check, but it
> looked that way, then it's 439 files, listed three times each, 410
> shared objects (libraries and plugins), 29 other files.  And the vlc
> files are all shared objects, 699/3=233 of them, 233 of the 410 shared
> objects.
> 
> > ATM, I have an eagle session on a pcb going in another window, pending
> > info that I screwed the moose, so I would rather get that fixed before
> > I reboot kde.
> 
> That's semi-gobbledegook, here, but given that in previous mails you've
> mentioned some sort of CAD/CAM setup, I'll assume that's what you're
> referring to.  Yeah, letting it finish doing whatever it's monitoring/
> controlling before a reboot might indeed be useful.

eagle is a pcb design package. With various feature sets, free to about 
$2500 a seat.  Obviously I'm using the free version.  I am taking its 
output, running that through pcb2gcode, and then etching the pcb on my toy 
milling machine.  ATM I am making the sensor board for a position encoder, 
which in turn will tell LinuxCNC where in the rotation my equally toy 
lathes spindle is, and knowing that, LinuxCNC can drive the carriage, 
either for a shaped normal turning, or even, using a single toothed tool, 
carve threads at even non-integer threads per inch (or cm)

That should explain some of the gobbledegook :)

> Meanwhile...
> 
> Some kde settings experimentation may be useful here, but one or more of
> the following should help.  Some are short term workarounds, some longer
> term potential fixes:
> 
> Short term: Under common appearance and behavior, application and system
> notifications, manage notifications, on the player settings tab, try
> setting no audio output.  This may or may not kill the existing locked
> up knotify4s, I'm not sure, but it should prevent the problem from
> reoccurring, assuming I'm correct and it is an audio issue of some
> sort, at least, because it simply no-ops the problematic calls.
> 
> Medium/long term:  In the same place, you can try setting an external
> player instead of kde's normal (phonon-based) sound system.  Back in
> kde3, I did this for awhile when arts was hopelessly screwed up, but
> I've not had to resort to it in kde4.
> 
> The trick is finding an appropriate player, probably setting it to
> no-gui if it's a gui player, etc.  I tried a couple things before I
> found a solution that "just worked" for me.  It involved the playsound
> binary from the sdl-sound package (installed here for something
> unrelated), but played at full volume, the sound effects overpowered
> whatever else I happened to be playing, so I ended up setting up a
> script that played it at reduced volume.
> 
> Here's $HOME/bin/playsound.sh (vol can be set up or down if necessary,
> but .5 was a good balance for me):
> 
> #!/bin/bash
> # To play something at a bit lower volume (1=100%, normal volume)
> vol=.5
> playsound --volume $vol $@
> 
> Then I just set playsound.sh as the player, and it worked.
> 
> 
> Short term, could be longer term if you like it, or QUICKLY shut off if
> you don't!:  Use a "visual bell" instead of sound effects.  This
> involves two configuration changes:
> 
> Under common appearance and behavior, application and system
> notifications, system bell, check use system bell instead of system
> notifications.
> 
> Under workspace appearance and behavior, workspace appearance,
> accessibility, on the bell tab:  Check use visible bell, and experiment
> with invert and flash screen, with timing, as desired.  You can set an
> audible bell as well, but you may not avoid the sound lockups, that way.
> 
> FWIW, I've used this before.  The effect can be disconcerting at first,
> especially if it happens when you're concentrating on something and have
> forgotten all about setting this up.  But it DOES tend to get your
> attention, as long as you're looking at the screen, of course.  The
> feature is designed for deaf folks (thus accessibility) or for use in
> meetings, etc, where a sound would be disruptive.  But it's a nice
> option to have.  Just don't have a heart attack the first time you're
> concentrating on something and the screen inverts/flashes!  As I said,
> it CAN be disconcerting, but forewarned is forearmed.
> 
> 
> The proper (user/admin-level) fix:  Depending on the exact nature of the
> problem and your hardware, this could take several forms.
> 
> As mentioned above, one trigger of the problem can be sound device power
> saving mode.
> 
> On a laptop that's battery powered much of the time, you probably want
> to keep that on to save power when you're not playing anything.  In
> that case, setting visual bell for notifications as suggested above is
> a good idea, since (a) that way you don't have to wake up the sound
> device just to play a notification ding, and (b), laptop/netbook use is
> far more likely to include use in meetings, etc, where the sound isn't
> desirable anyway.
> 
> If you do want to keep sound notifications on a laptop/netbook/etc, but
> still don't want to use too much battery running the sound device when
> there's nothing playing, playing around with its power-saving settings
> may be useful.  Setting a too short (say 1 second) idle-timeout is known
> to be highly problematic on some hardware.  It wasn't kde context, more
> like general alsa and kernel device driver context, but I happened upon
> this I think just yesterday, and it makes sense, 10 seconds is the
> recommended MINIMUM.  I'd actually suggest something like 30 seconds to
> perhaps even five minutes (or even 15, consider how much power those
> 100% CPU cycle apps will use!), since I believe part of the problem is
> race conditions where it gets a wakeup just as it was powering down,
> potentially leaving the app trying to play the sound thinking the
> device is responding, but it just powered down instead, so the app ends
> up waiting forever, especially if the device doesn't signal the app
> correctly when it does wake back up.
> 
> On a desktop/workstation that's on A/C power all the time, just disable
> audio device power saving entirely.
> 
> Unfortunately, directions for setting/disabling audio device power
> saving aren't something I can deal with here.  If kde deals with it at
> all, I don't have that bit of it installed, and individual device
> driver settings are likely to be just that, individual.  Check the docs
> or try posting to your distro's lists/forums.
> 
KDE doesn't handle that at all well yet IMO.
> 
> Another possible fix is device preference order.  This is in kde
> settings, hardware, multimedia, phonon.  When I first switched to the
> phonon-vlc backend, everything seemed to work great (far better than the
> phonon-xine backend, now not even available on some distros as upstream
> kde dropped support for it).  But somewhere in the 4.7 or 4.8 timeframe
> (I ran the 4.8 betas and rcs and don't remember exactly when it showed
> up), the previous config quit working so well.  Sound continued to work,
> but I'd get popups saying it was falling back to a different device as
> the preferred device wasn't working.
> 
> The fix was to select every possible device (unless you have multiple
> physical devices and want some routed differently, do this for audio
> playback itself, not the individual purposes, notifications, music, etc)
> and hit the test button.  If it works well, move it up.  If it doesn't,
> move it down.  Do this when you're having problems (sometimes, like
> right now, all devices test as working here, they didn't when I did the
> testing and reordered them when I had the problem).
> 
> My list of devices has four listed for one physical device, Default,
> which will play thru the alsa default device, normally the first one
> detected if there's multiple physical devices, and three different
> listings for the hardware (AMD AMD8111, in my case, one saying /just/
> that, one with the name twice, with "(Default Audio Device)" in
> parenthesis, one with the name twice, and "(hw:0,0)" in parenthesis).
> 
> I ended up with Default (no hardware name) at the top of the list.  The
> twice-listing with (Default Audio Device) next, the single-listing
> third, and the twice-listing with (hw:0,0) last.
> 
> Since then, I've had no more phonon-fallback notification popups. =:^)
> But I'm not entirely sure if I really fixed it, or if that was a beta/rc
> problem that was fixed with kde 4.8.0, or if I just haven't hit the
> conditions that triggered it again.  Whatever, I'm just happy to not be
> seeing those popups and thus worrying about sound (tho as I said, it did
> continue to work, I just saw the popups sometimes, and got worried).
> 
> Note that I didn't have the "breeding like rabbits" knotify4 problem
> here, at least that I noted (as I said I don't tend to stay up for more
> than a few days at a time, testing kernels, etc), only the irritating
> popup problem.  However, it could still be a device order issue, just
> with a slightly different manifestation than I had.
> 
> 
> Finally, it's also possible to switch phonon backends.  You apparently
> have phonon-vlc configured, as do I.  There's also the phonon-gstreamer
> backend, if you wish to try it.  The phonon-gstreamer backend /does/
> happen to be the kde (and gentoo) default, so it might be worth trying.
> 
> But I haven't tried it, mostly because I have bad memories about trying
> to get gstreamer to work a long time ago due to problems that are almost
> certainly long gone, so it'd probably work just fine now, but I've just
> never actually needed to install gstreamer as there have always been
> other alternatives that worked, so I haven't.  (Of course, the fact that
> I'm on gentoo and would thus have to build all those extra components
> just to try gstreamer out... when it would at least at first be for just
> one thing since I have alternatives to gstreamer installed for
> everything else, is part of the picture as well.  That's a big barrier
> to cross just to try it out.  If I were on a binary distro and all
> trying out gstreamer involved was downloading and installing pre-built
> binaries, the barrier would be lower, and there's a fair chance I'd
> have tried it again by now.)
> 
> Anyway, I can't say what the phonon-gstreamer backend might do
> different, but it could be worth trying, if you're having problems with
> phonon-vlc, especially if you're on a binary distro so don't have the
> high barrier to trying it out that I do, and/or if you already have
> gstreamer itself installed, as many binary distro users as well as
> gnome users, for other reasons.

Much of the above I skimmed through, but nothing went ding.  It hasn't come 
back again either, and I'm up 19.5 days now.  I will, the next time it 
happens, have htop sort on time and see if I can make any sense of it that 
way.  Sound was however, working all the way through that kill session.  
Still is.

Thanks Duncan

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
My web page: <http://coyoteden.dyndns-free.com:85/gene>
The probability of someone watching you is proportional to the
stupidity of your action.
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