This data-race occurred in Virtualbox with 3D acceleration enabled. Below is stack trace of this data race. This bug was fixed by upstream three years ago but it hasn't merged into our code. I have patched my library and Virtualbox haven't crashed since then.
Fix: https://cgit.freedesktop.org/xcb/libxcb/commit/?id=be0fe56c3bcad5124dcc6c47a2fad01acd16f71a [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1". Core was generated by `/usr/lib/virtualbox/VirtualBox --startvm Windows 10'. Program terminated with signal SIGABRT, Aborted. #0 0x00007f7c36b4fcc9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56 56 ../nptl/sysdeps/unix/sysv/linux/raise.c: No such file or directory. (gdb) bt #0 0x00007f7c36b4fcc9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56 #1 0x00007f7c36b530d8 in __GI_abort () at abort.c:89 #2 0x00007f7c36b48b86 in __assert_fail_base (fmt=0x7f7c36c99830 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x7f7c2b55a615 "!c->out.queue_len", file=file@entry=0x7f7c2b55a600 "../../src/xcb_conn.c", line=line@entry=186, function=function@entry=0x7f7c2b55a630 <__PRETTY_FUNCTION__.10950> "write_vec") at assert.c:92 #3 0x00007f7c36b48c32 in __GI___assert_fail (assertion=assertion@entry=0x7f7c2b55a615 "!c->out.queue_len", file=file@entry=0x7f7c2b55a600 "../../src/xcb_conn.c", line=line@entry=186, function=function@entry=0x7f7c2b55a630 <__PRETTY_FUNCTION__.10950> "write_vec") at assert.c:101 #4 0x00007f7c2b54ee5b in write_vec (count=0x7f7c00cd9ba4, vector=0x7f7c00cd9ba8, c=0x7f7c0835d020) at ../../src/xcb_conn.c:186 #5 _xcb_conn_wait (c=c@entry=0x7f7c0835d020, cond=cond@entry=0x7f7c0835e140, vector=vector@entry=0x7f7c00cd9ba8, count=count@entry=0x7f7c00cd9ba4) at ../../src/xcb_conn.c:490 #6 0x00007f7c2b54f191 in _xcb_out_send (c=c@entry=0x7f7c0835d020, vector=vector@entry=0x7f7c00cd9be0, count=count@entry=1) at ../../src/xcb_out.c:367 #7 0x00007f7c2b54f8a7 in _xcb_out_flush_to (c=0x7f7c0835d020, request=93593) at ../../src/xcb_out.c:394 #8 0x00007f7c2b54f9c8 in xcb_take_socket (c=0x7f7c0835d020, return_socket=return_socket@entry=0x7f7c2e3cf000 <return_socket>, closure=closure@entry=0x7f7c0835b9e0, flags=0, sent=sent@entry=0x7f7c00cd9c78) at ../../src/xcb_out.c:293 #9 0x00007f7c2e3cea38 in require_socket (dpy=0x7f7c0835b9e0) at ../../src/xcb_io.c:68 #10 0x00007f7c2e3cf259 in _XFlush (dpy=0x7f7c0835b9e0) at ../../src/xcb_io.c:511 #11 0x00007f7c2e3d1c75 in _XGetRequest (dpy=dpy@entry=0x7f7c0835b9e0, type=type@entry=43 '+', len=len@entry=4) at ../../src/XlibInt.c:1735 #12 0x00007f7c2e3cb0bb in XSync (dpy=dpy@entry=0x7f7c0835b9e0, discard=discard@entry=0) at ../../src/Sync.c:43 #13 0x00007f7c2ed380ab in dri2XcbSwapBuffers (pdraw=0x7f7bd01085a0, remainder=<optimized out>, divisor=0, target_msc=0, dpy=0x7f7c0835b9e0) at ../../../../src/glx/dri2_glx.c:815 #14 dri2SwapBuffers (pdraw=0x7f7bd01085a0, target_msc=0, divisor=0, remainder=<optimized out>, flush=<optimized out>) at ../../../../src/glx/dri2_glx.c:853 #15 0x00007f7bf63bac5b in ?? () from /usr/lib/virtualbox/VBoxOGLrenderspu.so #16 0x00007f7bf63bd1ec in ?? () from /usr/lib/virtualbox/VBoxOGLrenderspu.so #17 0x00007f7c367ce7cc in ?? () from /usr/lib/virtualbox/VBoxRT.so #18 0x00007f7c3684980c in ?? () from /usr/lib/virtualbox/VBoxRT.so #19 0x00007f7c370ea182 in start_thread (arg=0x7f7c00cda700) at pthread_create.c:312 #20 0x00007f7c36c1347d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111 (gdb) frame 4 #4 0x00007f7c2b54ee5b in write_vec (count=0x7f7c00cd9ba4, vector=0x7f7c00cd9ba8, c=0x7f7c0835d020) at ../../src/xcb_conn.c:186 186 assert(!c->out.queue_len); (gdb) ** Changed in: libxcb (Ubuntu) Status: Incomplete => Confirmed ** Tags added: trusty -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to libxcb in Ubuntu. https://bugs.launchpad.net/bugs/1179617 Title: qmlscene assert failure: qmlscene: ../../src/xcb_conn.c:180: write_vec: Assertion `!c->out.queue_len' failed. Status in Qt: Fix Released Status in libxcb package in Ubuntu: Confirmed Bug description: - Spontaneous crash without any apparent reason. - Except the web browser, no application was in use at the moment of the crash. Thanks fabio ProblemType: Bug DistroRelease: Ubuntu 13.10 Package: qmlscene 5.0.1-0ubuntu3 ProcVersionSignature: Ubuntu 3.9.0-1.5-generic 3.9.1 Uname: Linux 3.9.0-1-generic x86_64 ApportVersion: 2.10-0ubuntu3 Architecture: amd64 Date: Mon May 13 20:02:17 2013 EcryptfsInUse: Yes InstallationDate: Installed on 2012-10-12 (213 days ago) InstallationMedia: Ubuntu 12.04.1 LTS "Precise Pangolin" - Release amd64 (20121011) MarkForUpload: True SourcePackage: qtdeclarative-opensource-src UpgradeStatus: Upgraded to saucy on 2013-05-01 (11 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/qt/+bug/1179617/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
