[armedbear-devel] Pure threads and hashtables test

[Mark Evenson]

Attached find a test that abstracts all the file i/o away, and seemingly 
shows that there *is* a problem with concurrent hashtables access to ABCL.

CL-USER> (run 1)
Spawning 1 threads... Done.
Spawned threads that should sum to 10 while the shared value is 10.
NIL
CL-USER> (run 10)
Spawning 10 threads... Done.
Spawned threads that should sum to 100 while the shared value is 100.
NIL
CL-USER> (run 100)
Spawning 100 threads... Done.
Spawned threads that should sum to 1000 while the shared value is 993.
NIL

In this test, each thread sleeps for (/ (random 1000) 1000) seconds to 
allow contentions to arise.

Inspection of the code and observations of whether this test should be 
expected to "fail" for some other problem are solicited.


-- 
"A screaming comes across the sky.  It has happened before, but there
is nothing to compare to it now."
-------------- next part --------------
;;; Test for shared writes to a single hash entry for ABCL

#|
Use:

(run 2) 

(run 1000) 

|#

(defparameter *shared* (make-hash-table :test 'equal))

(defun increment (n)
  (sleep (/ (random 1000) 1000))
  (loop :for i :below n
     :doing (progn 
	      (sleep (/ (random 1000) 1000))
	      (setf (gethash 1 *shared*)
		    (1+ (or (gethash 1 *shared*)
			    0)))))
  n)

(defun run (threads)
  (clrhash *shared*)
  (format t "~&Spawning ~A threads..." threads)
  (format t " Done.~%Spawned threads that should sum to ~A while the shared value is ~A.~%"
	  (loop :for thread :in 
	     (loop :for i :below threads
		:collect (threads:make-thread (lambda () (increment 10))))
	     :summing (threads:thread-join thread))
	  (gethash 1 *shared*)))