[plt-scheme] Make multiple attempts to open DrScheme join running process?

On Sun, 2007-02-25 at 08:58 -0600, Matthew Flatt wrote:
> At Sun, 25 Feb 2007 02:20:32 -0500, "Todd O'Bryan" wrote:
> > On Sun, 2007-02-25 at 01:33 -0500, Eli Barzilay wrote:
> > > On Feb 24, Todd O'Bryan wrote:
> > > > As I've mentioned before, I'm running DrScheme in a thin terminal
> > > > lab and have 30 students sharing one server.
> > > 
> > > On a single machine?  I don't think that it's possible.
> > > 
> > It really is: http://www.ltsp.org/
> > 
> > I have one $2000 machine (dual dual-core Opterons with 4GB of RAM)
> > serving 30 stations that each cost $130 (not including monitor,
> > keyboard, and mouse). If you do the math, that's 30 stations for about
> > $200 each. The set-up usually works pretty well, even when I have 20
> > students all using Eclipse at once. Unfortunately, the whole thing
> > breaks down when the system starts to thrash, and it's only been doing
> > that, so far, in my intro classes where I use DrScheme.
> 
> How much memory does each DrScheme process use when the system starts
> to thrash? Close to the initial footprint, or much larger?
> 
> Although we don't have much hope for dramatic decreases in DrScheme's
> initial footprint, my guess is that DrScheme instances consume even
> more memory --- a lot more memory --- after students use each instance
> for a while. If so, that problem should be greatly reduced in the next
> version.
> 
It is quite a bit larger, so maybe the better garbage collector will
help.

Something else I'm going to try is an automatic re-nicer that several
people who use LTSP have suggested. If I put mred and drscheme on a list
of suspect binaries, it should keep them from taking over the whole
server. I guess I also need to figure out how to set memory limits more
at a finer level than the same for all users.

Thanks for looking out for possible improvements,
Todd