Multi user catalog and how to make it - use a checked out system

Question

Lots of people want or need a Multi user ability in lightroom here is one way to achieve multi-user catalogs by using a check-in check-out system.
The Catalog would open normally upon a second user opening LR would then ask to switch to multi-user mode.
Once in multi user mode lightroom would lock-out images, collections, or folders by a checked-out for editing system.
By checking-out images, collections, or folders: files would be unavailable to other users until edits are saved, and the images, collections, or folders are checked-in.
This check-in check-out system would need a global check-in feature in case someone forgot to check in an image, collection, or folders (global check-in could be admin level). Word documents, CAD files, etc, use a similar lock-out/read only system for the files. Since, we wouldn't want to bloat the files with programing to lock out the files, this would have to be added to the catalog and managed by the catalog.
My system
Vista Ultimate 32bit SP1
AMD 64X2 duel core 6000+ 3.2Ghz
6GB 666mhz Ram PAE force enabled
NVIDIA Gforce 7600 256MB video card (1.75GB total with system shared ram)
primary hard drive 500GB
Hard drive 2 400GB (system and photoshop paging files and lightroom catalog drive)
Hdrive 3 1TB (primary image storage)
user control turned off
system graphics set to performance
Duel display
LR 2.0
PS extended CS3

Answer 1

Your thread pool is a pool and probably keeps
the thread alive even though the thread has nothing
after a minute toi execute - you'll have to call its
shutdown() methodThanks Oxe...
I googled that (easy when you know what the answer is) and yes the ScheduledThreadPool retains threads for re-use, so you have to check that all threads are done and then shutdown() the scheduler... like this:     while (!future.isDone()) {
          try { Thread.sleep(10); } catch(InterruptedException e) {}
     scheduler.shutdown();
... here is the complete working class:
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledFuture;
import static java.util.concurrent.TimeUnit.*;
import java.awt.Toolkit;
class BeeperControl {
     private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
     public void beepForAMinute() {
          final Toolkit tk = Toolkit.getDefaultToolkit();
          final Runnable beeper = new Runnable() {
               public void run() {
                    tk.beep();
                    System.out.println("beep");
          final ScheduledFuture<?> future = scheduler.scheduleAtFixedRate(beeper, 250, 250, MILLISECONDS);
          scheduler.schedule(
               new Runnable() {
                    public void run(){
                         future.cancel(true);
               }, 3, SECONDS
          while (!future.isDone()) {
               try { Thread.sleep(10); } catch(InterruptedException e) {}
          scheduler.shutdown();
     public static void main(String[] args)
          BeeperControl bc = new BeeperControl();
          bc.beepForAMinute();
}Thanx again. Keith.