[Python-Dev] Can I make marshal.dumps() slower but stabler?

Ivan Pozdeev vano at mail.mipt.ru
Fri Jul 13 10:43:43 EDT 2018


If the use case for stability is only .pyc compilation, I doubt it's 
even relevant 'cuz .pyc's are supposed to be compiled in isolation from 
other current objects (otherwise, they wouldn't be reusable or would be 
invalidated when dependent modules change, neither of which is the 
case), so relevant reference counts should always be the same.
I may be mistaking though.

On 13.07.2018 16:57, Christian Tismer wrote:
> Well, to my knowledge they did not modify the marshal code.
> They are in fact heavily dependent from marshal speed since that
> is used frequently to save and restore state of many actors.
>
> But haven't looked further since 2010 ;-)
>
> Btw., why are they considering to make the algorithm slower,
> just because someone wants the algorithm stable?
>
> An optional keyword argument would give the stability, and the
> default behavior would not be changed at all.
>
> Cheers - Chris
>
>
> On 12.07.18 12:07, Steve Holden wrote:
>> Eve is indeed based on stackless 2, and are well capable of ignoring
>> changes they don't think they need (or were when I was working with
>> them). At one point I seem to remember they optimised their interpreter
>> to use singleton floating-point values, saving large quantities of
>> memory by having only one floating-point zero.
>>
>> Steve Holden
>>
>> On Thu, Jul 12, 2018 at 9:55 AM, Alex Walters <tritium-list at sdamon.com
>> <mailto:tritium-list at sdamon.com>> wrote:
>>
>>
>>
>>      > -----Original Message-----
>>      > From: Python-Dev <python-dev-bounces+tritium-
>>      > list=sdamon.com at python.org <mailto:sdamon.com at python.org>> On Behalf Of
>>      Victor Stinner
>>      > Sent: Thursday, July 12, 2018 4:01 AM
>>      > To: Serhiy Storchaka <storchaka at gmail.com <mailto:storchaka at gmail.com>>
>>      > Cc: python-dev <python-dev at python.org <mailto:python-dev at python.org>>
>>      > Subject: Re: [Python-Dev] Can I make marshal.dumps() slower but stabler?
>>      >
>>      > 2018-07-12 8:21 GMT+02:00 Serhiy Storchaka <storchaka at gmail.com <mailto:storchaka at gmail.com>>:
>>      > >> Is there any real application which marshal.dumps() performance is
>>      > >> critical?
>>      > >
>>      > > EVE Online is a well known example.
>>      >
>>      > EVE Online has been created in 2003. I guess that it still uses Python
>>      2.7.
>>      >
>>      > I'm not sure that a video game would pick marshal in 2018.
>>      >
>>
>>      EVE doesn't use stock CPython, IIRC.  They use a version of stackless 2,
>>      with their own patches.  If a company is willing to patch python
>>      itself, I
>>      don't think their practices should be cited without more context
>>      about what
>>      they actually modified.
>>
>>      > Victor
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-- 
Regards,
Ivan

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