[elephant-devel] Cannot allocate memory

[Walter C. Pelissero]

Ben writes:
 > I've commited the new changes.  Walter -- can you try your tests with
 > the new stuff?  (you'll need to upgrade to sleepycat 4.3, and do a
 > fresh cvs checkout.)

I downloaded the latest elephant and installed db-4.3.  The problem
didn't go away but I've been able to isolate it.  My program, in
certain situations, starts a complete scan of the database (summing
the value of a class slot).  This is done within a transaction that
somehow exausts Sleepycat resources.  Here is how to reproduce the
problem.

I run several times the following function with increasing START
values.  (Just iterating more times in the loop would trigger the DB
error, so I tried to avoid it.)

(defun load-elephant (start)
  (be btree (ensure-btree "test")
    (ele:with-transaction ()
      (loop
         with end = (+ start 100000)
	 for i from start by 1 below end
	 do (setf (ele:get-value i btree) i)))))

After having, say, one million items, I run the following function,
which doesn't do anything special beside counting the items in the
btree.

(defun crash-elephant ()
  (ele:with-transaction ()
    (elephant:with-btree-cursor (btree (ensure-btree "test"))
      (loop
	 with items = 0
	 for (ok key value) = (multiple-value-list (ele:cursor-first btree))
	 then (multiple-value-list (ele:cursor-next btree))
	 while ok
	 do (incf items)
	 finally (return items)))))

This should yield the DB error.

-- 
walter pelissero
http://www.pelissero.de