<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv=Content-Type content="text/html; charset=koi8-r"> <meta name=Generator content="Microsoft Word 12 (filtered medium)"> <style>  </style>  </head> <body lang=EN-US link=blue vlink=purple> <div class=WordSection1> Hi,<o:p></o:p> <o:p> </o:p> I’ve a program developed using xlib and cairo. Just for the reference I do mix calls between cairo and xlib, although I’m not sure If that might be the cause of the error.<o:p></o:p> I get a deadlock orš a block in some situations.<o:p></o:p> I’ve three threads that work with xlib. One is the main UI thread which makes calls to both xlib and cairo, another uses it just to send a XClientMessage and third makes some xlib calls like XCopyArea and at the end send an XClientMessage (those are for some animations).<o:p></o:p> I’ve called InitThreads in the beginning of the program. I’ve also guarded all xlib calls with XLockDisplay (cairo calls are also guarded with XLockDisplay). <o:p></o:p> I’m using ubuntu 10.10. <o:p></o:p> The stack traces are:<o:p></o:p> <o:p> </o:p> (gdb) thread 1<o:p></o:p> #0  0xb77e5430 in __kernel_vsyscall ()<o:p></o:p> #1  0xb71d8ba6 in poll () from /lib/tls/i686/cmov/libc.so.6<o:p></o:p> #2  0xb70dcd80 in ?? () from /usr/lib/libxcb.so.1<o:p></o:p> #3  0xb70dd2eb in ?? () from /usr/lib/libxcb.so.1<o:p></o:p> #4  0xb70dd687 in xcb_writev () from /usr/lib/libxcb.so.1<o:p></o:p> #5  0xb76ed2e9 in _XSend () from /usr/lib/libX11.so.6<o:p></o:p> #6  0xb76ed900 in _XEventsQueued () from /usr/lib/libX11.so.6<o:p></o:p> #7  0xb76d6588 in XPending () from /usr/lib/libX11.so.6<o:p></o:p> <o:p> </o:p> (gdb) thread 6<o:p></o:p> #0  0xb77e5430 in __kernel_vsyscall ()<o:p></o:p> #1  0xb75ac829 in __lll_lock_wait () from /lib/tls/i686/cmov/libpthread.so.0<o:p></o:p> #2  0xb75a7f3b in _L_lock_752 () from /lib/tls/i686/cmov/libpthread.so.0<o:p></o:p> #3  0xb75a7d51 in pthread_mutex_lock () from /lib/tls/i686/cmov/libpthread.so.0<o:p></o:p> #4  0xb76d311a in ?? () from /usr/lib/libX11.so.6<o:p></o:p> #5  0xb76d268a in XLockDisplay () from /usr/lib/libX11.so.6<o:p></o:p> <o:p> </o:p> (gdb) thread 7<o:p></o:p> #0  0xb77e5430 in __kernel_vsyscall ()<o:p></o:p> #1  0xb75ac829 in __lll_lock_wait () from /lib/tls/i686/cmov/libpthread.so.0<o:p></o:p> #2  0xb75a7f3b in _L_lock_752 () from /lib/tls/i686/cmov/libpthread.so.0<o:p></o:p> #3  0xb75a7d51 in pthread_mutex_lock () from /lib/tls/i686/cmov/libpthread.so.0<o:p></o:p> #4  0xb76d311a in ?? () from /usr/lib/libX11.so.6<o:p></o:p> #5  0xb76d268a in XLockDisplay () from /usr/lib/libX11.so.6<o:p></o:p> <o:p> </o:p> Where thread 1 is the main ui thread, currently calling XPending (it has already called XLockDisplay) in an event loop, thead 7 is the thread that just sends XClientMessage and thread 6 is the thread that has made some calls to XCopyArea and is now about to make a call to XSendMessage (it is waiting along with thread 7 for thread 1 to finish). But thread 1 never seem to return from poll.<o:p></o:p> I’m not sure it is relevant (I’m by no means an expert on linux or libc), but I’ve another thread waiting in poll (it’s a thread for TCP/IP network communication)<o:p></o:p> (gdb) thread 2<o:p></o:p> #0  0xb77e5430 in __kernel_vsyscall ()<o:p></o:p> #1  0xb71d8ba6 in poll () from /lib/tls/i686/cmov/libc.so.6<o:p></o:p> <o:p> </o:p> Has anyone experience similar deadlock/block? Can this be a bug in xcb and is it worth trying to compile xlib without xcb?<o:p></o:p> Thanks<o:p></o:p> <o:p> </o:p> </div> </body> </html>