Re: [Chicken-users] Posix threading

[felix winkelmann]

On Fri, 11 Mar 2005 09:41:08 +0100, Peter Busser <address@hidden> wrote:
> 
> > Perhaps Posix threaded programs could work, provided they only rely upon
> > "evicted" shared data?
> 
> If each stack evicts its own stack, this means that the heap is accessed
> concurrently and needs to be protected against this, because it will lead to
> race conditions and therefore corruption.
> 

Exactly.

But (slightly diverging from the original subject), with a non-preemptive
(i.e. cooperative) scheduling policy, as for example provided by GNU Pth,
one could run several stacks concurrently. This makes callouts to C
with dynamic-extent possible: C stack frames can then be GC'd. Also,
callback handling would be simpler. Effectively this means creating
a separate C stack for a call into C that might callback into Scheme.
[IIRC Bruce Butterfield suggested this some time ago]

Anyway, to share a common global heap, threads would be to
be synchronized at every minor GC, which is very often.


cheers,
felix