[Stackless] Stackless Digest, Vol 123, Issue 9

[Andrew Francis]

Hi Folks:

Some thoughts:

In playing with stackless.py, I liked the original version more than the current version.

In the original stackless.py, one had the choice of low-level concurrency, either greenlets if working with CPython, PyPy's coroutine library.

The latest version of stackless.py removed greenlet support. This is a pity. I liked the layering, separating high level API from low level concurrency. I grew up reading Andrew Tannenbaum and Douglas Comer. 

I originally directly hacked on stackless.py. Now I realise this was a really bad idea. One reason I haven't put join and select stuff in github is that I am trying to refactor the code so I can get it running on C based Stackless Python, CPython with greenlets, and PyPy. I have started. I have to revisit my notes to give specifics but I found that it helps if the scheduler stuff has more API functions. So one can even experiment with, say a channel re-implementation with Stackless Python (as opposed to with stackless.py). 

example:

selectStackless.py, code should look something like

# import underlying functionality
import stackless

# however we export selectStackless.py functionality
__all__ = 'run getcurrent getmain schedule tasklet channel select'.split()
# we re-implement channel 
class channel(object):
.
.
# and select
def select(.....):
       

layer 3 - select, join, channel-reimplementations,  whatever else 
layer 2 - channels
layer 1 - Tasklets, scheduler, atomic 
layer 0 - tealets, greenlets

As for PyPy continuations. I think the current problem is with pickling. When I have time, I'll look for the reference in the PyPy mailing list.

Cheers,
Andrew

Message: 1
Date: Sun, 13 Apr 2014 12:07:37 -0400
From: Alain Poirier <alain.poirier at net-ng.com>
To: stackless at stackless.com
Subject: [Stackless] Sprinting at PyCon
Message-ID: <5AC6D14B-8E76-488A-B07A-52A6008199A0 at net-ng.com>
Content-Type: text/plain; charset=windows-1252

Hi all,

I would like to discuss how it'd be possible or not for Stackless to follow the
same path than PyPy:

  - A simpler Stackless core, with only the 'tealet' / '_continuation' stack
    switch, writing in C. Exposing the same API than PyPy.
    IIRC, Krisjan already has such a Stackless version.

  - All the high level features of Stackless like Tasklets and Channels moved to
    the 'stackless.py' pure Python module.

  - An emulation of the greenlets API, in a 'greenlet.py' pure Python module.

  - Bonus point if these 'stackless.py' and 'greenlet.py? modeules are shared /
    co-developed with the PyPy project :)

I see several advantages then:

  - Greenlets and Stackless features being Python modules, easier experimentations
    are possible. For example writing other scheduling policy or higher concurrency
    primitives such like Andrew's select/join.

  - With a 'greenlet.py' compatible module, lots of softwares like ?gevent? could
    work without any modification.

  - Works on 'greenlet.py' and 'stackless.py' can profit both to Python Stackless
    and PyPy.

Just my 2 cents,
Alain




------------------------------

Message: 2
Date: Mon, 14 Apr 2014 09:48:56 +0200
From: Anselm Kruis <a.kruis at science-computing.de>
To: stackless at stackless.com
Subject: Re: [Stackless] Sprinting at PyCon
Message-ID: <534B92E8.5090102 at science-computing.de>
Content-Type: text/plain; charset="windows-1252"; format="flowed"

Hi Alain,

another unique feature of Stackless is pickling/unpickling of tasklets 
and many other python types. This feature is essential for many 
applications and probably needs some additional C-code besides 'tealet' 
/ '_continuation'. That said I like your proposal, but I doubt that we 
have enough man power to implement it.

Cheers
   Anselm

Am 13.04.2014 18:07, schrieb Alain Poirier:
> Hi all,
>
> I would like to discuss how it'd be possible or not for Stackless to follow the
> same path than PyPy:
>
>    - A simpler Stackless core, with only the 'tealet' / '_continuation' stack
>      switch, writing in C. Exposing the same API than PyPy.
>      IIRC, Krisjan already has such a Stackless version.
>
>    - All the high level features of Stackless like Tasklets and Channels moved to
>      the 'stackless.py' pure Python module.
>
>    - An emulation of the greenlets API, in a 'greenlet.py' pure Python module.
>
>    - Bonus point if these 'stackless.py' and 'greenlet.py? modeules are shared /
>      co-developed with the PyPy project :)
>
> I see several advantages then:
>
>    - Greenlets and Stackless features being Python modules, easier experimentations
>      are possible. For example writing other scheduling policy or higher concurrency
>      primitives such like Andrew's select/join.
>
>    - With a 'greenlet.py' compatible module, lots of softwares like ?gevent? could
>      work without any modification.
>
>    - Works on 'greenlet.py' and 'stackless.py' can profit both to Python Stackless
>      and PyPy.
>
> Just my 2 cents,
> Alain
>
>
> _______________________________________________
> Stackless mailing list
> Stackless at stackless.com
> http://www.stackless.com/mailman/listinfo/stackless
>

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------------------------------

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