[Bordeaux-threads-devel] Dead lock in condition wait.

[rayfill]

Hi.

I use condition-wait in many acquire recursive-lock. Other thread try
to acquire recusirve-lock's lock at dead locked.

Below code reproduce a problem on Clozure CL.
---
(defvar *condition-variable* (bt:make-condition-variable))
(defvar *recursive-lock* (bt:make-recursive-lock))

(defun worker-job (out)
  (bt:with-recursive-lock-held (*recursive-lock*)
    (bt:with-recursive-lock-held (*recursive-lock*)
      (format out "before condition wait~%")
      (force-output out)
      (bt:condition-wait *condition-variable* *recursive-lock*)
      (format out "after condition wait~%")
      (force-output out))))

(defun condition-use-in-recursive-lock ()
  (let* ((out *standard-output*)
	 (worker (bt:make-thread (lambda () (worker-job out)))))
    (sleep 1)
    (format out "before condition notify~%")
    (force-output out)
    (bt:with-recursive-lock-held (*recursive-lock*) ; Dead lock point.
      (bt:condition-notify *condition-variable*)
      (format out "after condition notify~%")
      (force-output out))
    (bt:join-thread worker)))

(condition-use-in-recurive-lock)
---

conditon-wait is lock release and wait semaphore.
Lock object acquirable many times. but conditon-wait is release lock at once.

I make a patch at here.
https://github.com/rayfill/bordeaux-threads/commit/192124d18a2b2858e6e8aa2cc0409065992d097a

Poor english sorry...


-- 
 rayfill at gmail.com
 Jiro OKAZAKI