[Xcb] Problem selecting event input from different threads.

Erik De Rijcke derijcke.erik at gmail.com
Mon Apr 19 02:56:41 PDT 2010


I've tested with the latest xlib and xcb from git master.

These are the results I'm getting.

Xcb: same results as described earlier

when using xlib with xcb backend:
XInithreads on or off makes no difference.
XSynchronized set to true makes things hang quite frequently but I do get
events, setting it to false gives the same situation as xlib with xcb
back-end.

I'll try to make a simple unit test (Java with C) that replicates
this behavior if it would help squashing this bug?


On Mon, Apr 19, 2010 at 12:32 AM, Jamey Sharp <jamey at minilop.net> wrote:

> On Sun, Apr 18, 2010 at 1:31 PM, Erik De Rijcke <derijcke.erik at gmail.com>
> wrote:
> > I have a fairly large program with a small part accessing xcb. It
> basically
> > does the following:
> > thread A: open a display; spawn thread b; listen for events.
> > thread B: set event mask (substructure redirect mask on root window)
> > What seems to happen is that thread A never gets any configure request
> > events nor map requests. However when I replicate this exact code with
> Xlib
> > with build in xcb backend, thread A does receive events.
> > I'm guessing only the thread that sets the mask gets the events, is there
> a
> > way to tell xcb to deliver the events to thread A or is this a possible
> bug?
>
> I'm guessing this is a bug I finally tracked down yesterday. :-)
>
> Can you re-test with current libxcb from git master?
>
> I'm a little surprised you had success with current Xlib/XCB though. I
> have some fairly hefty patches I'm testing right now (`ico -threads
> 16` is running on another desktop) to squash several Xlib threading
> bugs. Have you noticed the Xlib version of your code dying sometimes
> with assertion failures, or hanging?
>
> Thanks,
> Jamey
>
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