Attachment 599842 Details for Bug 842403 – IRC log of the discussion

IRC log of the discussion

irc_log.txt (text/plain), 7.90 KB, created by kushaldas@gmail.com on 2012-07-23 19:07:30 UTC

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Creator: kushaldas@gmail.com

Created: 2012-07-23 19:07:30 UTC

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patch

obsolete

>* ngalvin has quit (Quitting)
><mclasen> more like some python program runs into a deadlock ?
><dmalcolm> mclasen: apparently it's hanging
><dmalcolm> (we were discussing it on #fedora-python, hopefully kushal can give more info)
> #fedora-releng #fedora-python #fedora-mktg #fedora-kde #fedora-india #fedora-fudcon #fedora-docs #fedora-devel #fedora-cloud #fedora-art #fedora-arm #fedora-apps #fedora-admin #fedora-desktop 
><kushal> mclasen, from #fedora-python , <Zart> f15, Â«DISPLAY= python -c 'import gtk'Â» throws runtimeerror: could not open display
><kushal> mcepl, though I used wrong words, sorry for that 
><mclasen> not exactly surprising, if you unset DISPLAY...
><halfline> import gtk connects to your display, if you have display set to an empty string it won't have anything to connect to
><kushal> halfline, mclasen ok, completely forgot about that 
><mclasen> its a quirk of the gtk bindings that importing them opens a display connection
>* mclasen was never a python person, so no opinion on the merits of that approach
><kushal> mclasen, yes, anyway to identify the cause ?
><mclasen> the cause of what ?
><kushal> this strange python import ?
><dmalcolm> kushal: iirc the issue you ran into was that "import gtk" was hanging
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><kushal> dmalcolm, the bt is from modules command 
><kushal> dmalcolm, I never saw this, the new python/Fedora students tried out python tutorial and started crying over this 
><dmalcolm> kushal: I know, but you're in a new channel and need to give more context when you ask a question
><kushal> dmalcolm, sorry :(
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><kushal> pasting full details 
><kushal> mclasen, http://fpaste.org/kIpD/ this is when it hangs 
><kushal> mclasen, http://fpaste.org/soiO/ is the corresponding bt
><dmalcolm> it's doing an "import gtk"
><dmalcolm> oh, is there a chance that it might have tried to init gtk twice in the same process?
>* dmalcolm wonders if that would cause problems
><dmalcolm> (the "modules" command tries to import every module on the system, so tends to run into issues with buggy modules)
><aspektor> ping Company 
><halfline> dmalcolm: that's why i was thinking
><halfline> *what
><halfline> basically the module is getting loaded and then unloaded
><halfline> you can't do that for statically registered types
><halfline> s/module/gtk library/
><halfline> only explanation i can come up with anyway
><halfline> easy way to verify would be to LD_PRELOAD libgtk-2
><halfline> and see if the problem vanishes
><dmalcolm> that gdk_window_get_type() hang: did GObject types gain a mutex a while back?
><dmalcolm> looks like it's stuck waiting on a mutex that it'll never get
><mclasen> gtype has always had locks
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><dmalcolm> ah
><mclasen> you can't reenter type initialization, which is why calling random functions from a type init() is a  bad idea
><halfline> this works: LD_PRELOAD=/usr/lib64/libgtk-x11-2.0.so python
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><halfline> so my guess is
><mclasen> or are you loading gtk2 and gtk3 bindings in the same process ?
><halfline> no no no
><halfline> that's not the problem
><danw> iirc, you can reenter type initialization within a single thread, you just can't initialize types in two threads at once
><halfline> the problem is a plugin is getting loaded that links against libgtk
><mclasen> in which case the same type names between gtk2 and gtk3 would kill you
><halfline> and then that plugin is getting unloaded
><halfline> so gtk is getting dlopened() and closed
><halfline> and then the next plugin comes along
><halfline> and gtk gets opened again
><halfline> then all those static variables will have bogus data in them
><halfline> from the last time it was opened
><kushal> halfline, the preload magic http://fpaste.org/j2fh/ 
><mclasen> halfline: well, the static variables go away if the module is really unloaded
><mclasen> the problem is that the static type registration is not getting undone, right ?
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><halfline> i don't believe the static variables go away when the module is unloaded, but i could be wrong
><mclasen> either way, the problem stems from not respecting that libraries are not in general unloadable
><halfline> at any rate, g_type_info_register_static very specifically doesn't allow this sort of thing
><halfline> looks like ld has a nodelete option
><kushal> so anyway to fix or avoid this issue ?
><mclasen> kushal,dmalcolm: not sure if this discussion helped you...
>* dmalcolm is not sure either
><halfline> there are two potential solutions i can think of
><halfline> 1) run LD_DEBUG=all python 
><halfline> to find out which module is dlopening libgtk
><halfline> and then change it to dlopen with NODELETE as a flag
><halfline> 2) investigate -z nodelete linker option and see if it can be used when creating the shared object file to make gtk be opened NODELETE automatically
><halfline> then rebuild gtk with said option
><dmalcolm> kushal: this ought to be in bz too
><halfline> gah it's clutter
><mclasen> halfline: I'd rather not have hacks in gtk to make things work 'somewhat'
><kalev> why isn't this an issue when loading/unloading browser plugins that link with gtk, e.g. flash?
><Company> aspektor: pong
><mclasen> kalev: because the browsers generally link against gtk
><Company> plugins have their own process these days, too
><halfline> infact flash doesn't work in epiphany right now because epiphany is gtk3 and flash is gtk2
><aspektor> Company: âhey, I am still stuck with this Tracker widget, for some reason events I try to trigger (on button press in my case) just does not work, could you please take a look here: http://fpaste.org/K3dz/ maybe you could see what's wrong ?
><kushal> dmalcolm, ok, filing now, should I put it against gtk ?
><halfline> mclasen: oh you're right also actually
><mclasen> I didn't see anything here that would compel me to 'fix' gtk
><halfline> looking at the LD_DEBUG output
><halfline> it's loading gtk2 and gtk3
><Company> aspektor: you need to subscribe to the events I guess - see http://developer.gnome.org/gtk/2.24/GtkWidget.html#gtk-widget-add-events
><dmalcolm> kushal: pygtk2 I think
><halfline> so yea, i don't see how this command can work
><kushal> dmalcolm, ok, doing it 
><aspektor> Company I have add events on line 43
><halfline> http://fpaste.org/XLuZ/
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><halfline> look at line 36      15603: file=/lib64/libgdk-3.so.0 [0];  needed by /lib64/libgtk-x11-2.0.so.0 [0] (relocation dependency)
>* dtardon has quit (This parrot is dead.)
><Company> aspektor: you don't seem to gtk_widget_show() the widget?
><Company> or rather, you show the widget when it gets clicked - but invisible windows can't be clicked...
><aspektor> Company:  What I want to achieve is that window to appear only when mouse is pressed and disappear on release
><halfline> dmalcolm, kushal: hmm a quick-and-dirty solution might be for the modules command to load each module in a subprocess
><dmalcolm> halfline: interesting idea
><aspektor> Company: do you think it is better to just rewrite release event so it destroy/hide the widget ? (me tried it but it does not seem to work too)
><Company> aspektor: i'd leave the old event handling code in place
><Company> aspektor: and use this new widget only for displaying
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><kushal> dmalcolm, but that means patching python, correct ?
><aspektor> Company: but when I do gtk_widget_show it shows widget right away correctly ? Than how can I make it to show widget only on Button Press ?
><aspektor> P.S even if I put gtk_widget_show it still does not trigger gtk_button_press_event ...
><dmalcolm> kushal: yes, but that command often causes problems; I'd be up for trying that (once I've finished working on 3.3, that is)
><Company> aspektor: by creating the widget only when a button is pressed

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Attachments on bug 842403: 599840 | 599842 | 599847 | 599852 | 600062