Created attachment 130799 [details] reproducer g.c When logged into localhost as root via SSH, XOpenDisplay() blocks for more than 60 s about every other time it is called: #0 0x00007f48d4209c90 in __connect_nocancel () from /lib64/libc.so.6 #1 0x00007f48d3ee8409 in _xcb_open_tcp () from /lib64/libxcb.so.1 #2 0x00007f48d3ee87a4 in xcb_connect_to_display_with_auth_info () from /lib64/libxcb.so.1 #3 0x00007f48d4507a3a in _XConnectXCB () from /lib64/libX11.so.6 #4 0x00007f48d44f8772 in XOpenDisplay () from /lib64/libX11.so.6 #5 0x00000000004007bf in main () at g.c:19 For reference, I mistakenly filed this as a GTK bug first: https://bugzilla.gnome.org/show_bug.cgi?id=781182 The system is Fedora 25: ~> uname -a Linux drift.m.i2n 4.10.8-200.fc25.x86_64 #1 SMP Fri Mar 31 13:20:22 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux ~> rpm -qi xorg-x11-server-Xorg Name : xorg-x11-server-Xorg Version : 1.19.3 Release : 1.fc25 Architecture: x86_64 Install Date: Mon 03 Apr 2017 09:49:02 AM CEST Group : User Interface/X Size : 3744258 License : MIT Signature : RSA/SHA256, Thu 30 Mar 2017 06:26:25 PM CEST, Key ID 4089d8f2fdb19c98 Source RPM : xorg-x11-server-1.19.3-1.fc25.src.rpm Build Date : Wed 15 Mar 2017 07:39:18 PM CET Build Host : buildhw-03.phx2.fedoraproject.org Relocations : (not relocatable) Packager : Fedora Project Vendor : Fedora Project URL : http://www.x.org Summary : Xorg X server
Created attachment 130800 [details] strace of reproducer triggering the delay, see gap between 17:27:44 and 17:28:48
The only things that can really cause XOpenDisplay to block are reloading the XAUTHORITY file and (maybe) doing hostname lookups. It would be informative to strace the _server_ when running this test to see what it's doing, since clearly all the delay is happening there.
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