I’m going out hence a short reply.
There are various options for -d and the manual may have more details on the options.
-d {all,act_on,cache,camctl,camsupport,control,demosaic,dev,imageio,
input,ioporder,lighttable,lua,masks,memory,nan,opencl,params,
perf,print,pwstorage,signal,sql,tiling,undo,verbose}
Interesting, as I got a never-ending parade of activity in my terminal
Yes that is normal. You may need to pipe the output to a file to allow you to browse through it.
If you have a graphics card installed try running darktable --disable-opencl to disable the graphics card to see if opencl is causing the issue.