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[Stackless] Re: [Python-Dev] Stackless Design Q.

Jeff Senn senn@maya.com
Wed, 20 Feb 2002 11:00:37 -0500 
Greg Ewing <greg@cosc.canterbury.ac.nz> writes:
> It's not clear exactly what you're after here. Are you
> trying to define the lowest-level interface upon which
> everything else will be built? If so, I think what you
> have presented is FAR too complex.
>
> It seems to me you need only two things:
...
>    t = tasklet(f)
>    t.transfer()

(Sorry if I missed something -- I've been *way* busy lately and
haven't been giving this much attention -- that said...)

But (if I understand the current plan) we will need mechanisms
internal to the Python interpreter to transfer values and maintain
blocked/running state anyway; since when you generate a tasklet and
run it:

 t = tasklet(f)
 t.transfer()

That may cause many more tasklets to be generated, run, and destroyed
that you don't ever see ...  recursions/function calls in f, and
only-Christian-knows what else...  so the transfer value mechanism
might as well be built in.

I haven't thought enough about the "unamed produce-and-continue
function" to decide how exactly it should work.

I have two concerns in implementing uthreads this way (scheduler in
C):

 1 -- there doesn't seem to be anyway to "kill" a tasklet
 2 -- the scheduling algorithm will be hard to tune (we'll probably
      *at least* need tasklet priority...)  Maybe there should still
      be a "timeslice" function so an in-Python scheduler can be written?

-- 
-Jas   --------------------     www.maya.com
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