[Xcb] libxcb/libX11 deadlocking and asserting in multi-threaded use

Nicholas Allen nick.allen at onlinehome.de
Fri Mar 19 03:18:53 PDT 2010


I found this bug report in Launchpad:

This is the exact same assertion that I am seeing. On this page:


I see that the bug has confirmed status and high importance. Is anyone
on this list working on this bug? I am also willing to help fix it if I
can (and someone will be willing to put up with my questions as I become
familiar with the code).



Jamey Sharp wrote:
> Nicholas Allen wrote:
>> ../../src/xcb_io.c:242: process_responses: Assertion `(((long)
>> (dpy->last_request_read) - (long) (dpy->request)) <= 0)' failed.
>> Aborted
> This is not the most recent version of libX11, but I think newer
> changes shouldn't matter.
> There was a bug report recently that had this assertion failure as its
> symptom. That turned out to be an X server bug (failure to byte-swap
> the sequence number field in certain replies) and it only affected
> setups where the client was on a machine with a different endianness
> than the server. You're not doing that, are you?
> http://bugs.freedesktop.org/show_bug.cgi?id=26511
> On Fri, Mar 19, 2010 at 1:22 AM, Nicholas Allen
> <nick.allen at onlinehome.de> wrote:
>> Sorry that code is not complete. I wasn't calling XFlush after mapping
>> the window. I'll try to make a more complete  version that reproduces
>> this bug...
> I was just wondering why I didn't see the window mapped when I noticed
> you'd sent this mail. :-) Good catch. Of course you also need an
> XFlush after each XResizeWindow. Given those changes, I'm not seeing
> either a hang or an assertion failure.
> Thank you for taking the time to get to a minimal test case, though.
> When you've found something that reliably reproduces the bug, it will
> help a lot.
> Jamey
> _______________________________________________
> Xcb mailing list
> Xcb at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/xcb

More information about the Xcb mailing list