Hi,

Continued.

Of course one could also implement a copy-on-write-bit for objects in 
the "read-only-shared-top-level-object-space-of-the-image". In order to 
accomplish any work a process must be forked! Also, this way any process 
that forks off will need to copy all of the objects it modifies into 
it's own private object-space until the process commits it's changes 
into the top level object-space or until it aborts. That's assuming a 
Software Transactional Memory scheme is added to Smalltalk.

Actually this idea is quite appealing if done right.

Of course there are a host of other awesomely complex problems implied 
by the above that a simple concurrency model will NOT solve.

Concurrency isn't like automatic garbage collection - which is actually 
quite broad and complex a field - at all. The sets of problems with 
concurrent systems are way more complex. This is especially the case 
when you bring distribution beyond a single compute node into the fold 
and especially when other issues such as distributed garbage collection 
are required. Welcome to the complex world of tomorrow today.

What do the actual vendor's staff who write the virtual machines think 
about this?

All the best,

Peter William Lount