Interrupting the program "xv" via ctrl-C results in 100% CPU hog.
The gdb backtrace shows:

#0  0xb7c2cb6e in poll_for_reply (c=0x822a768, request=5112, reply=0xbf93e194, 
    error=0xbf93e208) at xcb_in.c:258
#1  0xb7c2ce43 in xcb_wait_for_reply (c=0x822a768, request=5112, e=0xbf93e208)
    at xcb_in.c:343
#2  0xb7e8bafb in _XReply (dpy=0x822a008, rep=0xbf93e230, extra=0, discard=1)
    at xcb_io.c:364
#3  0xb7e7f71a in XSync (dpy=0x822a008, discard=0) at Sync.c:48
#4  0x080627ea in Quit (i=1) at xvmisc.c:597
#5  <signal handler called>
#6  0xb7f8a410 in __kernel_vsyscall ()
#7  0xb7cff55d in select () from /lib/libc.so.6
#8  0xb7c2b165 in _xcb_conn_wait (c=0x822a768, cond=0x822a7c8, vector=0x0, 
    count=0x0) at xcb_conn.c:318
#9  0xb7c2cb3c in xcb_wait_for_event (c=0x822a768) at xcb_in.c:391
#10 0xb7e8b2a1 in wait_or_poll_for_event (dpy=0x822a008, wait=-1080826180)
    at xcb_io.c:100
#11 0xb7e8b5cf in process_responses (dpy=0x822a008, wait_for_first_event=1, 
    current_error=0x0, current_request=0) at xcb_io.c:115
#12 0xb7e72aab in XNextEvent (dpy=0x822a008, event=0xbf93e938)
    at NextEvent.c:50
#13 0x080600c8 in EventLoop () at xvevent.c:129
#14 0x08057c15 in main (argc=1, argv=0xbf93ec74) at xv.c:3710
#15 0xb7c58fe0 in __libc_start_main () from /lib/libc.so.6
#16 0x0804d101 in _start ()