[gradsusr] problems running GrADS on MacBook Pro 16"

[Geert Jan van Oldenborgh]

Not sure whether this has been discussed here before, but I finally found the solution for running grads on the shiny MacBook Pro 16" with Catalina that my boss kindly granted me. Both the MacPorts version and the COLA download version hang on startup after opening the X window. Tracing down the stack I found that the problem is in the shared library /opt/X11/lib/libX11.6.dylib, which I think is from XQuartz. If you replace this with a symlink to the MacPorts version at /opt/local/lib/, grads runs fine.

Geert Jan van Oldenborgh
KNMI

Details:
Pressing ^C in lldb gives a stack

libsystem_pthread.dylib`_pthread_cond_wait
libxcb.1.dylib`_xcb_conn_wait
libxcb.1.dylib`_xcb_out_send
libxcb.1.dylib`xcb_writev
libX11.6.dylib`_XSend
libX11.6.dylib`XQueryExtension
libX11.6.dylib`XInitExtension
libXrender.1.dylib`XRenderExtAddDisplay
libXrender.1.dylib`XRenderFindDisplay
libXrender.1.dylib`XRenderQueryVersion
libcairo.2.dylib`_cairo_xlib_device_create
libcairo.2.dylib`_cairo_xlib_screen_get
libcairo.2.dylib`cairo_xlib_surface_create
libgxdCairo.0.dylib`gxdbgn
grads`gxstrt
grads`gagx
grads`main

These shared librarries are loaded from

/opt/local/lib/libxcb.1.dylib -> libxcb.1.1.0.dylib
/opt/X11/lib/libX11.6.dylib 

That one is very old (I assume from XQuartz), when I remove that file and symlink the MacPorts alternative things work.