[Pharo-dev] [Vm-dev] Re: Nuking VM ImageSegment support (was Re: [squeak-dev] Daily Commit Log; System-bf.916)

[Max Leske]

Hi Eliot,

> On 22 Sep 2016, at 20:46, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> 
> Hi Max,
> 
> On Thu, Sep 22, 2016 at 11:42 AM, Max Leske <maxleske at gmail.com <mailto:maxleske at gmail.com>> wrote:
>  
> 
>> On 22 Sep 2016, at 20:28, Eliot Miranda <eliot.miranda at gmail.com <mailto:eliot.miranda at gmail.com>> wrote:
>> 
>> Hi Bert, Hi All,
>> 
>> On Thu, Sep 15, 2016 at 2:55 PM,  <commits at source.squeak.org <mailto:commits at source.squeak.org>> wrote:
>> [snip]
>> http://lists.squeakfoundation.org/pipermail/packages/2016-September/068930.html <http://lists.squeakfoundation.org/pipermail/packages/2016-September/068930.html>
>> 
>> Name: System-bf.916
>> Ancestors: System-bf.915
>> 
>> Replace VM-level ImageSegment loading with a Smalltalk implementation for old (interpreter-era) projects.
>> 
>> Also removes support for writing segments.
>> 
>> This overrides the Spur support introduced in System-eem.758.
>> 
>>  So one question is should we delete VM support for ImageSegment from the Spur VM?  There's at least 1.5k of generated source for the Spur ImageSegment load and save support, some 2% of the interpreter/primitives source code.  That's a lot, and the code is complex and ugly.  If it never really worked before IMO we should nuke it asap.  If it worked in some fashion perhaps we can schedule its demise for the 6.0 release's VM.
>> 
>> What do others think?
> 
> As long as you don’t remove it from the Cog VM’s until I no longer need it I’m fine with that.
> 
> And when would that be?

Can’t really say but I'm hoping to get rid of ImageSegment within the next 2 years (very rough estimate).

>   Do you mean that you use it in ways not covered by Bert's modifications (which render the VM support superfluous), or do you mean that you use ImageSegment as a naive consumer and are happy just so long as it works?

Speed is important to me, as I use ImageSegment to create snapshots of our applications (and hence I need write support, which Bert apparently removed). Those snapshots can exceed 90 MB and the graphs include thousands of objects. I fear that a pure Smalltalk implementation would not be fast enough.


On the other hand, we would simply not move to a VM version without ImageSegment support, so that case may give me the boost I need to get rid of ImageSegment :) Currently we’re preparing to move to our first Cog VM in production. If you can give me 2 or 3 months, so that I know the version we use works for us, you could then remove ImageSegment support and we would start replacing ImageSegment with something else so we could keep updating our VM.

Cheers,
Max

>  
> 
> Max
> 
>> 
>> _,,,^..^,,,_
>> best, Eliot
> 
> 
> 
> 
> 
> -- 
> _,,,^..^,,,_
> best, Eliot

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