In [Tcl]-land, we often discourage use of [threads], for reasons documented 
elsewhere [[explain]].  Here's an example of how to think about design involving
threads:

Briefly, Tcl applications need threads when they rely on long-running external
resources, like database look-up or communications with physical devices 
[[references]].  Even in the latter case, though, there are a number of 
alternatives:
   * [[explain [bgexec] ]]
   * [[more generally, rely on process interface]]
   * [[ [fconfigure]-ation of [serial port] communications]] [[note recent [USB] corrections]]

[[Use of [dqkit] as a great convenience.]]