[Stackless] For interested - an interlacing compiler for C that allows continuations

Christian Tismer tismer at tismer.com
Sun Sep 8 18:31:14 CEST 2002

Aaron Watters wrote:

> How about going the other direction and emulate tasklets
> in processes?

You think to use/extend the tasklet interface to
be capable at real processes as well?

> I've been beginning to wish for process/pseudo tasklets.
> The bad thing about my http experiments so far is that if one
> cgi script crashes the whole server dies.  It would be cool if
> I could write stackless style multistage programs that reside
> in separate processes and communicate using channels.  Then if
> one crashes, it's more like conventional http/cgi, big deal.

You can catch every exception in the main tasklet, to
prevend the whole system from crashing. On the other hand,
if a tasklet really hangs, the system is of course hosed.
Well, I have a raise_exception ready which raises an exception
in any tasklet, and I will finish a kill() today which
raises SystemExit in a tasklet and captures the exception.
What I'm still planning for is a brutal kill_hard() which
bypasses the exception mechanism as a last resort, really
cleans the C stack and gives the tasklet no chance to
escape (but also no chance to do clean-up).

But I'm really interested to extend tasklets/channels
to do inter-process communication. I'm also looking into
MPI, to support multiple CPUs and machines in a standardized

> What would be even cooler would be if I could take a
> tasklet/process which has gone dorment and pickle it, storing
> it away in a database for the time when the activity wakes up.
> If you could do this with a C program in a portable manner
> that would be great.

Pickling would really take advantage of such an ANSI C
approach. I've spent nearly a hundred of hours with C stack
analysis, but didn't find a really universal solution, yet.

ciao - chris
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