I'd like to call your attention to two packages that leverage SLIME's swank debugging protocol.  The first  https://github.com/brown/swank-client is an implementation of the client side of swank.  With Swank Client one Lisp process can send forms to a remote Lisp for evaluation.  If a condition is signaled in the remote Lisp, you can see the stack trace in Emacs and debug it.  Here's some ASCII art that shows the swank connections:  Emacs/Slime ---- Master Lisp ---- Remote Lisp Swank Crew uses Swank Client to create worker pools of remote Lisp jobs.  You can then use functions like PARALLEL-MAPCAR or PARALLEL-REDUCE to evaluate forms across many worker Lisp jobs. Here's another picture: Emacs/Slime | Master Lisp | | | | | ---- Worker Lisp 1 | ------ Worker Lisp 2 --------- Worker Lisp 3 Let me know if you give either of these libraries a try. bob