When an evaluation fails or is interrupted, it may be convenient to automatically kill tasks created during the evaluation. One use for this might be for debugging a set of long-running tasks. Here is a solution using alexandria’s unwind-protect-case.

(defpackage :example (:use :cl :lparallel :alexandria))
(in-package :example)

(defun call-with-kill-on-abort (fn task-category)
  (let ((*task-category* task-category))
    (unwind-protect-case ()
        (funcall fn)
      (:abort (kill-tasks task-category)))))

(defmacro with-kill-on-abort ((&key (task-category '*task-category*))
                              &body body)
  `(call-with-kill-on-abort (lambda () ,@body) ,task-category))

(defun foo ()
  (with-kill-on-abort (:task-category 'foo-stuff)
    (pmap nil #'sleep '(9999 9999))))

Example run in SLIME:

CL-USER> (example::foo) ; ... then hit C-c-c
WARNING: lparallel: Replacing lost or dead worker.
WARNING: lparallel: Replacing lost or dead worker.
; Evaluation aborted on NIL.

As always, worker threads are regenerated after being killed.