I have located the culprit! It does not have anything
to do with our code, rather with Tcl. It seems that
stdin/stdout/stderr channels are not properly handled
on thread exit (not detached from the interp).
This is a can of worms that I'm now opening...
I hate to fiddle with that stuff in Tcl core as it is
pretty confusing and complicated (and needs rewrite!)
In my multimedia Tcl application i've similar problems at that time i
just used C level orutines for output but
i remember i used cleanup code from Aolserver and had errors on thread exit
