Eliot Miranda-2 wrote:
>
> On Fri, Dec 18, 2009 at 6:04 PM, Martin McClure
> <martin@hand2mouse.com>wrote:
>
>> Stan Shepherd wrote:
>> > Pharo image: Pharo | Pharo-core
>> > PharoCore1.0rc1 Latest update: #10502
>> > VM: unix - i686 - linux-gnu - Pharo0.1 of 16 May 2008 [latest update:
>> > #10074]
>> >
>> > Steps to reproduce:
>> > 1.[Object allSubInstances size inspect] timeToRun �375479 (6 minutes)
>> >
>> > with fix
>> > [Object allSubInstances size inspect] timeToRun �22335 (22 seconds)
>> >
>> > Attached treats Object as a special case, and takes advantage of
>> primitive
>> > in SystemNavigation>>allObjectsDo:
>>
>> It looks like with this change, Object allSubInstances would return
>> instances of classes that do not inherit from Object, for instance
>> objects that inherit from ProtoObject.
>>
>> Perhaps the special case should go on ProtoObject? Or a test could be
>> made of how many subclasses a class has, and if it's over some arbitrary
>> number just iterate through all objects and test each one for isKindOf:?
>> Don't know how fast that would be, maybe it's not faster. But probably
>> slow is preferable to incorrect. If you just want "all objects" and
>> don't care about their class then you can always use
>> SystemNavigation>>allObjectsDo: rather than allSubInstances.
>>
>
> +1.
>
> I don't think there's any justification for this hack. �It's possible to
> have another root to the hierarchy apart from ProtoObject. �Further, a bit
> weak, but allSubInstancesDo: has ordering properties; it will evaluate the
> block with all instances of a class followed by all instances of another
> and
> so on; it will visit all instances of any superclass before it visits any
> instances of subclasses, and that could be useful. �If you want to use
> allObjectsDo: use it. �Of course allSubInstancesDo: is slow; it makes as
> many scans of the system as there are classes (Metaclass avoids the scan
> by
> evaluating with soleInstance). �But that's not a justification for
> special-casing one use of it to a freely accessible but different
> alternative.
>
>
>> Regards,
>>
>> -Martin
>>
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Eliot Miranda-2 wrote:
>
> I don't think there's any justification for this hack.
>

Quite so. It was late, and I'd thought better of it by morning. However,
don't feel you need to spare my feelings ;)

Taking a step back, Object allSubinstances size seems to be a common proxy
measure for the size/bloat/complexity of an image.
(E.g. http://www.object-arts.com/docs/index.html?how_many_objects.htm ).
Running it on a large production system would potentially be very slow.
It could also be something a current Smalltaker would run to check out
Pharo,
in which case a coffee break would be warranted. So from a marketing of
Pharo
perspective, 6 minutes seems too long to me. Yes, an experienced user will
avoid it.
I have no proposal as to how to catch that case while avoiding a hack.
Adding a specific
allSubinstances to Object class would break inheritance chain to Behavior.


In the meantime, perhaps there should be an alternative simple measure
available:

SystemNavigation>>allObjects
� � � �"A fast way to list all current objects in the image.
� � � �n.b. this will include the classes ImageSegmentRootStub MessageCatcher
� � � �TestCoverage DynamicBindingsInfo, and possibly others, that do not
� � � �inherit from Object. These classes probably have no instances, but
� � � �it is not safe to assume this"
� � � �| aCollection |
� � � �aCollection := OrderedCollection new.
� � � �self allObjectsDo:
� � � � � � � �[:x | x == aCollection ifFalse: [aCollection add: x]].
� � � �^ aCollection

with a comment in allSubInstances
� � � �"for Prototype>>allSubInstances, Object>>allSubInstances,consider using
� � � �SystemNavigation>>allObjects. This is much faster. see comment there"

Martin McClure wrote:
>
> It looks like with this change, Object allSubInstances would return
> instances of classes that do not inherit from Object, for instance
> objects that inherit from ProtoObject.
>

Yes. It doesn't currently, but it could. See comment above.

Martin McClure wrote:
>
> Or a test could be made of how many subclasses a class has, and if it's

> over some arbitrarynumber just iterate through all objects and test each

> one for isKindOf:?
> Don't know how fast that would be, maybe it's not faster.
>

Yes, I looked at that:
� � � � � � �multi �single
� � � � � � �pass � �pass
Collection � �18650 �29448 � � 82 subclasses, multipass 50% faster

BorderedMorph 26301 �7464 � 206 subclasses, singlepass 3x faster

GRObject � �113717 � 6969 � 742 subclasses, singlepass 14x faster.

Breakeven point is around 100 subclasses.

Mostly allSubInstances is used in housekeeping tasks, so it's not a big
issue.
As it's mostly used in housekeeping, a lot of the applications would
probably be
fine with the unordered, one pass version.

I'll do a bit of digging into whether there are any meaningful performance
implications.

...Stan

Behavior>>allSubInstancesDoInOnePass: �attached if anyone wants to benchmark
http://n2.nabble.com/file/n4192013/Behavior-allSubInstancesDoInOnePass.st
Behavior-allSubInstancesDoInOnePass.st
--
View this message in context: http://n2.nabble.com/Issue-1634-Object-allSubInstances-slooooow-tp4189848p4192013.html

Sent from the Pharo Smalltalk mailing list archive at Nabble.com.

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