[plt-scheme] Appalling performance of DrScheme on Windows

From: Jens Axel Søgaard (jensaxel at soegaard.net)
Date: Tue Jun 20 14:41:06 EDT 2006

Matthew Flatt skrev:
> Thanks to all who have provided information so far!
> One extra question to those who see bad behavior when DrScheme has been
> idle for a long time: do you use Help Desk's search feature?
> I ask because a Help Desk search goes through a servlet (using a local
> instance of the web server that runs through pipes instead of TCP
> connections). I wonder whether servlet session time-out could have
> something to do with the problem (either in the web server or in
> MzScheme's support for the web server).

On a low-memory machine it can be an advantage not to use HelpDesk.
My impression has always been that it isn't the HelpDesk it self
causing problems, but rather that starting the HelpDesk brings
down the available ram under a (perceived) critical treshold.

An observation: If I by accident write a program that allocates a
lot of ram and run it in DrScheme, fix the problem and rerun the
program, DrScheme seems to hang on to the allocated memory.

For example:

(define (alloc n size)
     (let ((vs (let loop ((n size))
                 (if (= n 0)
                     (cons (make-vector size)
                           (loop (- n 1)))))))
       (length vs)))

In the interaction window after a

(alloc 10000 1000000)

I got an out of memory error and the known bug icon. In the Windows
Job List I can see DrScheme now holds 1.888.922 KB of RAM. Hitting the
execute icon doesn't decrease this amount. [I think, I think it should]

Jens Axel Søgaard

Posted on the users mailing list.