Lock Failed Fatal Error
From X-Plane Wiki
This issue affects X-Plane version 8 on Linux. This issue does not affect X-Plane version 9 on Linux.
Some distros of Linux will give this error when running any X-Plane 864-generation application or installer.
xcb_xlib.c:50: xcb_xlib_unlock: Assertion 'c->xlib.lock' failed.
The problem is that libxcb became a lot more picky about reentrancy, breaking about a billion different packages...do a google search on that assert to see the fallout! (Apparently AWT was among the offenders.)
As far as I can tell most distros that have this problem have an environment variable to turn checking off, so you can run x-plane like this:
LIBXCB_ALLOW_SLOPPY_LOCK=1 ./sim
(or whatever is appropriate for your favorite shell). If this does not fix this problem, you'll need to find out how to get the xcb patch for your particular distro.
As far as I can tell, running with the sloppy locks environment variable does not affect sim performance in any way. X-Plane 9 does not have this problem.
Alternatively you could insert
export LIBXCB_ALLOW_SLOPPY_LOCK=true
at the end of your "/etc/profile" file. This turns the check off on every boot.