[pypy-dev] connecting multiple interpreters

[Christian Tismer]

On 6/4/12 4:26 PM, Michael Foord wrote:
>
>
> On 4 June 2012 14:33, Armin Rigo <arigo at tunes.org 
> <mailto:arigo at tunes.org>> wrote:
>
>     Hi Martijn, hi Holger,
>
>     On 6/1/12, Martijn Faassen <faassen at startifact.com
>     <mailto:faassen at startifact.com>> wrote:
>     > Concerning performance overhead of proxies, lifecycle issues
>     would be
>     > tricky
>
>     If, hypothetically speaking, there is someone interested in writing a
>     PyPy solution where both a Python2 and a Python3 interpreter are
>     running in the same process, then you gain the advantage of having
>     only one GC to run both.  At least it transparently solves the issues
>     of lifetime and reference cycles.  (You also have for free only one
>     JIT, which can do cross-language optimizations like inlining a Python2
>     function into a Python3 context or vice-versa).  I see these two
>     points as benefits that you don't have in any multi-process solution.
>
>     It would require some work on the PyPy side, and I'm not aware of
>     anybody ready to invest time in that, but it shouldn't be particularly
>     hard (once PyPy's Python3 interpreter is ready, and once people agree
>     about which API to use to do cross-language calls.)
>
>
>
>
> Having multiple interpreter instances within a single process allows 
> for lots of interesting possibilities. IronPython permits this and it 
> was used  by Resolver One - just one of the reasons (along with the 
> GIL) that it would have been much harder to write Resolver One in 
> CPython than in IronPython (although .NET was chosen as a platform 
> before Python was chosen as an implementation language).
>
> Allowing Python 2 and Python 3 to live within the same process would 
> be very interesting.

I too like this idea very much, because _that_ removes the need for a 
decision which
I really can't base upon taste, but module availabilities, 
PyPy-readiness etc.
Such a bridge would be very cool and quite 'peace-making' if may say so.

When thinking of it, a slightly crazy concern popped up:
I just followed the pyvenv discussions. PEP 405 will not be back-ported
to Python2.7.
If we now have two interpreter versions in one binary, which one of
the Janus-heads will lead decisions like pyvenv startup?

just-semi-seriously ;-) -- chris

-- 
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