[Vm-dev] SequenceableCollection VM crash (was Re: [Pharo-users] XMLOrderedList Concantenation)

Mon May 5 17:58:38 UTC 2014

2014-05-05 19:53 GMT+02:00 Nicolas Cellier <
nicolas.cellier.aka.nice at gmail.com>:

>
>
>
> 2014-05-05 19:27 GMT+02:00 Ben Coman <btc at openinworld.com>:
>
>>
>>  Just reporting, while looking into a query on [pharo-users] (which is
>> attached for initial context only and can probably be deleted from any
>> replies) I managed to crash the VM by evaluating the following in Workspace:
>>
>> a := SequenceableCollection new.
>> a add: 1.
>> a , SequenceableCollection new.
>>
>> Now the interesting thing is that while the system becomes immediately
>> sluggish, Pharo.exe crashes about 20 seconds later.
>>
>> This is with Pharo 3.0 Release (30846)
>> http://files.pharo.org/platform/Pharo3.0-win.zip (dated 2014-04-30)
>> on Windows Home Premium 64-bit SP1.
>>
>> cheers -ben
>>
>>
> SequenceableCollection is supposed to be abstract.
> above code causes an infinite loop because size is implemented in terms of
> do: and do: sends size.
>

Note that the VM terminates with an out of memory, but it seems that the
infinite loop is triggered while logging the debugger call stack in a file,
and this logging seems to be performed in background now, thus the sluggish
behavior.

>
>> Ben Coman wrote:
>>
>>
>> Thanks. That info made it much easier to try.  Sorry I didn't end up with
>> an answer for you, but I confirm there is some issue here, or something new
>> I can learn when other chip in.
>>
>> Here is what I tried.
>>
>> * Installed XMLParser (monty.58) from Configuration Browser in Pharo 3.
>>
>> * Ran your code. Got the same error.
>>
>> * From the call stack I observed that
>> XMLOrderedCollection(SequenceableCollection)>>copyReplaceFrom:to:with:
>> has the line "newSequenceableCollection := self species new: newSize."
>> such that it seems your error might be reduced to the question of why the
>> following two snippets fail:
>>     d := OrderedCollection new: 1.
>>     d at: 1 put: 1.
>>
>>     e := OrderedCollection new: 3.
>>     e at: 2 put: 1.
>>
>> However I'm sorry that is beyond my knowledge, and I'm hoping someone
>> else can chip in so I can learn something.
>>
>> Pushing on, I noticed that XMLOrderedList has an instance variable
>> /collection/ which holds the OrderedCollection.
>>
>> Now I wonder (without great experience and hoping to learn something) if
>> it smells funny that XMLOrderedList inherits all of SequencableCollection
>> methods that can not operate on /collection/.
>>
>> I noticed that XMLOrderedList was using an inherited
>> SequenceableCollection>>copyReplaceFrom:to:with
>> while OrderedCollection overrode that method with its own. So taking
>> inspiration XMLOrderedList>>copyFrom:to: to override
>> SequencableCollection>>copyReplaceFrom:to:with: to work with /collection/
>> seems to solve your problem:
>>     XMLOrderedList>>copyReplaceFrom: start to: stop with:
>> replacementCollection
>>         ^ self newWithCollection:
>>             (collection copyReplaceFrom: start to: stop with:
>> replacementCollection )
>>
>>
>> Along the way I noticed a few (possible) bugs that seems not related to
>> your problem:
>>
>> * When stepping through XMLOrderedList>>setCollection:
>> there is a red-box-of-death for the instance variables, which can be
>> solved by defining the following.
>>     XMLOrderedList>>size
>>         ^ collection ifNil: [ 0 ] ifNotNil: [ collection size]
>>
>> * In the debugger the /collection/ instance variable is not shown! (e.g.
>> line XMLOrderedList>>at:put:).
>> Can someone confirm this should show?
>>
>> HTH
>> cheers -ben
>>
>> Thushar G R wrote:
>>
>> XMLOrderedList belongs to package XML-Parser-Nodes.
>>
>>  a := XMLOrderedList new.
>> a add:'1'.
>> a , XMLOrderedList new.
>>
>>  Here select all and Do it. On line 3 (a , XMLOrderedList new.)  i am
>> expected to get a copy of 'a' , but instead it throws an error
>> SubscriptOutOfBounds.
>>
>>
>>
>>
>>  OrderedCollection(Object)>>errorSubscriptBounds:
>> OrderedCollection>>ensureBoundsFrom:to:
>> OrderedCollection>>at:put:
>> OrderedCollection(SequenceableCollection)>>replaceFrom:to:with:startingAt:
>> XMLOrderedList>>replaceFrom:to:with:startingAt:
>> XMLOrderedList(SequenceableCollection)>>copyReplaceFrom:to:with:
>> XMLOrderedList(SequenceableCollection)>>,
>> UndefinedObject>>DoIt
>> OpalCompiler>>evaluate
>> SmalltalkEditor>>evaluateSelectionAndDo:
>> PluggableTextMorph>>inspectIt in Block: [ textMorph editor
>> evaluateSelectionAndDo: [ :resu...etc...
>> PluggableTextMorph>>handleEdit: in Block: [ result := editBlock value ]
>> TextMorphForEditView(TextMorph)>>handleEdit:
>> PluggableTextMorph>>handleEdit:
>> PluggableTextMorph>>inspectIt
>> SmalltalkEditor class>>buildSmalltalkEditorKeymappingsOn: in Block: [
>> :morph | morph inspectIt ]
>> BlockClosure>>cull:
>> BlockClosure>>cull:cull:
>> BlockClosure>>cull:cull:cull:
>> KMCategoryBinding>>completeMatch:buffer:
>> KMKeymap>>notifyCompleteMatchTo:buffer: in Block: [ :l | l completeMatch:
>> self buffer: aBuffer ]
>> Array(SequenceableCollection)>>do:
>> KMKeymap>>notifyCompleteMatchTo:buffer:
>> KMKeymap>>onMatchWith:notify:andDo:
>> KMCategory>>onMatchWith:notify:andDo: in Block: [ :entry | entry
>> onMatchWith: anEventBuffer notify...etc...
>> Set>>do:
>> KMCategory>>onMatchWith:notify:andDo:
>> KMCategoryBinding>>verifyMatchWith:notifying:thenDoing:
>> KMDispatcher>>dispatch: in Block: [ :aTarget | ...
>> OrderedCollection>>do:
>>
>>
>>  Plese refer to the above stack.
>>
>>  Thanks in advance.
>>
>>  thushar
>>
>>
>> On Mon, May 5, 2014 at 6:28 PM, Ben Coman <btc at openinworld.com> wrote:
>>
>>>  Thushar G R wrote:
>>>
>>>> Hi,
>>>>
>>>> I am getting an error while doing this.
>>>>
>>>> a := XMLOrderedList new.
>>>> a add:'1'.
>>>> a , XMLOrderedList new.
>>>>
>>>> Thanks,
>>>>
>>>> Thushar
>>>>
>>>  I could give you "an answer" ;) - but it would be what you wanted.  It
>>> would help if you told what the error was, where it occurs (which of the
>>> three lines), and what you expect each line is doing (especially the third
>>> line).
>>>
>>> Also I don't see XMLOrderedList in the default Pharo image, so it would
>>> help if you describe where you got that from and how you installed it.
>>>
>>> cheers -ben
>>>
>>>
>>
>>
>>
>>
>
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