.lisp

(defun parse-logs (stream)
  (let ((channel (lparallel:make-channel))
        (count 0)
        (bad 0))
    (loop for line = (read-line stream nil nil)
          while line
          when (json-line-p line)
            do (incf count)
               (lparallel:submit-task
                channel
                (let ((line line))
                  (lambda ()
                    (multiple-value-list (ignore-errors (parse-line line)))))))
    (loop repeat count
          for (result error) = (lparallel:receive-result channel)
          if error
            do (incf bad)
          else if (slowlog-p result)
                 collect result into slowlogs
          else if (grok-fail-p result)
                 collect result into groklogs
          finally (return (values slowlogs groklogs bad)))))