Megatest

	 (registry-mutex         (runs:dat-registry-mutex runsdat))
	 (flags                  (runs:dat-flags runsdat))
	 (keyvals                (runs:dat-keyvals runsdat))
	 (run-info               (runs:dat-run-info runsdat))
	 (all-tests-registry     (runs:dat-all-tests-registry runsdat))
	 (run-limits-info        (runs:dat-can-run-more-tests runsdat))
	 ;; (runs:can-run-more-tests run-id jobgroup max-concurrent-jobs)) ;; look at the test jobgroup and tot jobs running
	 (have-resources         (car run-limits-info))
	 (have-resources         (and (if *journal-stats*
					  (let* ((dbfname (conc
							   (dbfile:run-id->dbnum run-id)
							   ".db"))
						 (stats (tt:get-journal-stats))
						 (load  (or (alist-ref dbfname stats equal?) 0)))
					    (if (> load 0.1) ;; dbs too busy to start more tests
						(begin
						 (debug:print-info 0 *default-log-port* "Gating launch due to db load "load" based on journal file observations for "dbfname)
						 #f)
						#t))
					  #t) ;; if journal monitoring not started do not gate
				      (car run-limits-info)))
	 (num-running            (list-ref run-limits-info 1))
	 (num-running-in-jobgroup(list-ref run-limits-info 2)) 
	 (max-concurrent-jobs    (list-ref run-limits-info 3))
	 (job-group-limit        (list-ref run-limits-info 4))
	 ;; (prereqs-not-met        (rmt:get-prereqs-not-met run-id waitons hed item-path mode: testmode itemmaps: itemmaps))
	 ;; (prereqs-not-met         (mt:lazy-get-prereqs-not-met run-id waitons item-path mode: testmode itemmap: itemmap))
	 (fails                  (if (list? prereqs-not-met) ;; TODO: rename fails to failed-prereqs

    (tt:write-load-tracking dbdir)
    (mutex-unlock! *journal-stats-mutex*)
    (thread-sleep! (/ (random 1000) 100.0))
    (loop)))

;; call this to start a thread that is keeping the journal-stats up to date.
(define (tt:start-stats dbdir)
  
  (thread-start!
   (make-thread
    (lambda ()(tt:journal-stats-run dbdir)) "Journal stats collection thread")))

(define (tt:get-journal-stats)
  (let* ((result    (make-jstats))
	 (hitcounts (jstats-jcount result)))

	(debug:print 0 *default-log-port* "INFO: *journal-stats* not set."))
    ;; convert to normalized alist
    (let ((tot  (min (jstats-count result) 1)) ;; avoid divide by zero
	  (hits (jstats-jcount result))) ;; 1.db => count
      (hash-table-map
       hits
       (lambda (fname hitcount)
	 (cons fname (/ hitcount tot)))))
	 (cons fname (/ hitcount tot)))))))
    ))

;; megatest> (import tcp-transportmod)
;; megatest> (tt:write-load-tracking ".mtdb")
;; megatest> (hash-table-keys *journal-stats*)
;; (172060297)
;; megatest> (jstats->alist (hash-table-ref *journal-stats* 172060297))
;; ((count . 1) (jcount . #<hash-table (1)>))
;; megatest> (jstats-jcount (hash-table-ref *journal-stats* 172060297))
;; #<hash-table (1)>
;; megatest> (hash-table->alist (jstats-jcount (hash-table-ref *journal-stats* 172060297)))
;; (("1.db" . 4))

)