[Xcb] [Socket handoff] Waiting forever...

Clemens Eisserer linuxhippy at gmail.com
Fri Jan 2 09:51:32 PST 2009


I am using the new socket-handoff functionality to mix protocoll
generated by XLib and some self-written protocol.
I am experiencing strange problems, where XCB seems to wait forever on
the server - like the stack-traces illustrate at the end of the email.

This seems to happen only sporadically, but it seems that workloads
with fewer larger requests (like many 32x32x8 putimages) more often.
I was able to find a reliable testcase which does 100000
putimage+composition. With only 10000 everything seems to work as
My output-buffer is 32k, so flushes happen quite often in both cases.
I have seen such behaviour previously when I sent misformated protocol
to the server, however this time it works 10000 times, but not 100000
- although I write exactly the same commands to the buffer again and

I spent a lot of time trying to hunt this problem down, but no luck so far :-/
Any ideas what could be wrong, or how I could debug the problem?

Thank you in advance and a happy new year, Clemens

#0  0xb7f9d416 in __kernel_vsyscall ()
#1  0x009885f1 in select () from /lib/libc.so.6
#2  0x7fe29035 in _xcb_conn_wait () from /opt/xorg/lib/libxcb.so.1
#3  0x7fe2b33a in xcb_wait_for_reply () from /opt/xorg/lib/libxcb.so.1
#4  0x7fe93078 in _XReply () from /opt/xorg/lib/libX11.so.6
#5  0x7fe877ea in XSync () from /opt/xorg/lib/libX11.so.6
#6  0x7ff8ac18 in X11SD_GetSharedImage ()
#7  0x7ff8c57c in X11SD_GetRasInfo ()
#8  0x7ffda2ac in Java_sun_java2d_loops_Blit_Blit ()

#0  0xb7f24416 in __kernel_vsyscall ()
#1  0x009885f1 in select () from /lib/libc.so.6
#2  0xacc5a035 in _xcb_conn_wait () from /opt/xorg/lib/libxcb.so.1
#3  0xacc5c33a in xcb_wait_for_reply () from /opt/xorg/lib/libxcb.so.1
#4  0xaccc4078 in _XReply () from /opt/xorg/lib/libX11.so.6
#5  0xaccbd7fb in _XPrivSyncFunction () from /opt/xorg/lib/libX11.so.6
#6  0xacc992cc in XChangeProperty () from /opt/xorg/lib/libX11.so.6
#7  0xacdb5ede in Java_sun_awt_X11_XlibWrapper_XChangePropertyImpl ()

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