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Weird rehashing problem

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Max Leske
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Weird rehashing problem

Max Leske
Hi

I have a rather strange problem with rehasing that occurred simultaneously multiple times on the same day but not since. Luckily I’ve saved an image with the debugger in it. The mean thing is: that doesn’t help me at all because from what I can tell either the Debugger is broken or there’s a VM problem.

Note:
The image is a Pharo 1.3 image. The problem occurred on two different VMs independently, an NBCog VM (Croquet Closure Cog VM [CoInterpreter VMMaker-oscog-EstebanLorenzano.166] 21.0) and a Squeak VM (Squeak3.10.2 of '5 June 2008' [latest update: #7179]).
The operation during which this happened was the loading of an ImageSegment (in both instances).


Here’s what happened. I got a SubscriptOutOfBounds error during rehashing of a Dictionary. When I look at the debugger it’s clear why the exception got signaled but not how that situation could ever happen.

These are the top three contexts on the stack:

Array(Object)>>errorSubscriptBounds:
Array(Object)>>at:put:
CBConfiguration(Dictionary)>>noCheckAdd:

This is the #noCheckAdd: method”

noCheckAdd: anObject
        "Must be defined separately for Dictionary because (self findElementOrNil:) expects a key, not an association.  9/7/96 tk"

        array at: (self findElementOrNil: anObject key) put: anObject.
        tally := tally + 1

and here’s #at:put: where the exception is signaled:

at: index put: value
        <primitive: 61>
        index isInteger ifTrue:
                [self class isVariable
                        ifTrue: [(index >= 1 and: [index <= self size])
                                        ifTrue: [self errorImproperStore]
                                        ifFalse: [self errorSubscriptBounds: index]] <——— signaled
                        ifFalse: [self errorNotIndexable]].
        index isNumber
                ifTrue: [^self at: index asInteger put: value]
                ifFalse: [self errorNonIntegerIndex]

Here’s the weird thing: according to the debugger ‘array' in #noCheckAdd: IS NOT THE SAME INSTANCE as ‘self’ in #at:put:!!!!!! ????????? When I look at the pointers to both arrays, the correct one is pointed to by the dictionary while the other is only being referenced by the exception context:

Bad array:
1: SubscriptOutOfBounds: 88
2: Array(Object)>>errorSubscriptBounds:
3: Array(Object>>at:put:
4: an Inspector
…

Good array:
1: aCBConfiguration(size 107)


I really have no clue how this could have happened. I’d appreciate any thoughts you might have…

Cheers,
Max
Dale Henrichs-3
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Re: Weird rehashing problem

Dale Henrichs-3
Don't know whether it's related or not, but just the other day I was updating builderCI to use the zeroconf scripts for Pharo1.2 through Pharo1.4 when I hit a problem loading a package from smalltalkhub that only failed (consistently) for Pharo1.3[1] and when I reverted to using the relatively old vm built into builderCI the loading problem disappeared[2] ... and I concluded that there was something in Pharo-3.0 that did not play well with the recent vm(only as Pharo-1.2 and Pharo-1.4 seemed to work fine).

The old vm suits my purposes just fine, but I would agree that there is something fishy there related to the vms ...

Dale

On Fri, Oct 24, 2014 at 7:29 AM, Max Leske <[hidden email]> wrote:
Hi

I have a rather strange problem with rehasing that occurred simultaneously multiple times on the same day but not since. Luckily I’ve saved an image with the debugger in it. The mean thing is: that doesn’t help me at all because from what I can tell either the Debugger is broken or there’s a VM problem.

Note:
The image is a Pharo 1.3 image. The problem occurred on two different VMs independently, an NBCog VM (Croquet Closure Cog VM [CoInterpreter VMMaker-oscog-EstebanLorenzano.166] 21.0) and a Squeak VM (Squeak3.10.2 of '5 June 2008' [latest update: #7179]).
The operation during which this happened was the loading of an ImageSegment (in both instances).


Here’s what happened. I got a SubscriptOutOfBounds error during rehashing of a Dictionary. When I look at the debugger it’s clear why the exception got signaled but not how that situation could ever happen.

These are the top three contexts on the stack:

Array(Object)>>errorSubscriptBounds:
Array(Object)>>at:put:
CBConfiguration(Dictionary)>>noCheckAdd:

This is the #noCheckAdd: method”

noCheckAdd: anObject
        "Must be defined separately for Dictionary because (self findElementOrNil:) expects a key, not an association.  9/7/96 tk"

        array at: (self findElementOrNil: anObject key) put: anObject.
        tally := tally + 1

and here’s #at:put: where the exception is signaled:

at: index put: value
        <primitive: 61>
        index isInteger ifTrue:
                [self class isVariable
                        ifTrue: [(index >= 1 and: [index <= self size])
                                        ifTrue: [self errorImproperStore]
                                        ifFalse: [self errorSubscriptBounds: index]] <——— signaled
                        ifFalse: [self errorNotIndexable]].
        index isNumber
                ifTrue: [^self at: index asInteger put: value]
                ifFalse: [self errorNonIntegerIndex]

Here’s the weird thing: according to the debugger ‘array' in #noCheckAdd: IS NOT THE SAME INSTANCE as ‘self’ in #at:put:!!!!!! ????????? When I look at the pointers to both arrays, the correct one is pointed to by the dictionary while the other is only being referenced by the exception context:

Bad array:
1: SubscriptOutOfBounds: 88
2: Array(Object)>>errorSubscriptBounds:
3: Array(Object>>at:put:
4: an Inspector
…

Good array:
1: aCBConfiguration(size 107)


I really have no clue how this could have happened. I’d appreciate any thoughts you might have…

Cheers,
Max
Eliot Miranda-2
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Re: [Vm-dev] Weird rehashing problem

Eliot Miranda-2
In reply to this post by Max Leske
Hi Max,

On Fri, Oct 24, 2014 at 7:29 AM, Max Leske <[hidden email]> wrote:

Hi

I have a rather strange problem with rehasing that occurred simultaneously multiple times on the same day but not since. Luckily I’ve saved an image with the debugger in it. The mean thing is: that doesn’t help me at all because from what I can tell either the Debugger is broken or there’s a VM problem.

I'm interested in taking a look at that image...  (and I'm relieved you saw it on both the Cog and the Interpreter VMs ;-) )

Note:
The image is a Pharo 1.3 image. The problem occurred on two different VMs independently, an NBCog VM (Croquet Closure Cog VM [CoInterpreter VMMaker-oscog-EstebanLorenzano.166] 21.0) and a Squeak VM (Squeak3.10.2 of '5 June 2008' [latest update: #7179]).
The operation during which this happened was the loading of an ImageSegment (in both instances).


Here’s what happened. I got a SubscriptOutOfBounds error during rehashing of a Dictionary. When I look at the debugger it’s clear why the exception got signaled but not how that situation could ever happen.

These are the top three contexts on the stack:

Array(Object)>>errorSubscriptBounds:
Array(Object)>>at:put:
CBConfiguration(Dictionary)>>noCheckAdd:

This is the #noCheckAdd: method”

noCheckAdd: anObject
        "Must be defined separately for Dictionary because (self findElementOrNil:) expects a key, not an association.  9/7/96 tk"

        array at: (self findElementOrNil: anObject key) put: anObject.
        tally := tally + 1

and here’s #at:put: where the exception is signaled:

at: index put: value
        <primitive: 61>
        index isInteger ifTrue:
                [self class isVariable
                        ifTrue: [(index >= 1 and: [index <= self size])
                                        ifTrue: [self errorImproperStore]
                                        ifFalse: [self errorSubscriptBounds: index]] <——— signaled
                        ifFalse: [self errorNotIndexable]].
        index isNumber
                ifTrue: [^self at: index asInteger put: value]
                ifFalse: [self errorNonIntegerIndex]

Here’s the weird thing: according to the debugger ‘array' in #noCheckAdd: IS NOT THE SAME INSTANCE as ‘self’ in #at:put:!!!!!! ????????? When I look at the pointers to both arrays, the correct one is pointed to by the dictionary while the other is only being referenced by the exception context:

Bad array:
1: SubscriptOutOfBounds: 88
2: Array(Object)>>errorSubscriptBounds:
3: Array(Object>>at:put:
4: an Inspector
…

Good array:
1: aCBConfiguration(size 107)


I really have no clue how this could have happened. I’d appreciate any thoughts you might have…

Cheers,
Max



--
best,
Eliot
Max Leske
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Re: [Vm-dev] Weird rehashing problem

Max Leske

On 24.10.2014, at 20:49, Eliot Miranda <[hidden email]> wrote:

Hi Max,

On Fri, Oct 24, 2014 at 7:29 AM, Max Leske <[hidden email]> wrote:

Hi

I have a rather strange problem with rehasing that occurred simultaneously multiple times on the same day but not since. Luckily I’ve saved an image with the debugger in it. The mean thing is: that doesn’t help me at all because from what I can tell either the Debugger is broken or there’s a VM problem.

I'm interested in taking a look at that image...  (and I'm relieved you saw it on both the Cog and the Interpreter VMs ;-) )

Cool! I’ll send you a private message with a link to the image.


Note:
The image is a Pharo 1.3 image. The problem occurred on two different VMs independently, an NBCog VM (Croquet Closure Cog VM [CoInterpreter VMMaker-oscog-EstebanLorenzano.166] 21.0) and a Squeak VM (Squeak3.10.2 of '5 June 2008' [latest update: #7179]).
The operation during which this happened was the loading of an ImageSegment (in both instances).


Here’s what happened. I got a SubscriptOutOfBounds error during rehashing of a Dictionary. When I look at the debugger it’s clear why the exception got signaled but not how that situation could ever happen.

These are the top three contexts on the stack:

Array(Object)>>errorSubscriptBounds:
Array(Object)>>at:put:
CBConfiguration(Dictionary)>>noCheckAdd:

This is the #noCheckAdd: method”

noCheckAdd: anObject
        "Must be defined separately for Dictionary because (self findElementOrNil:) expects a key, not an association.  9/7/96 tk"

        array at: (self findElementOrNil: anObject key) put: anObject.
        tally := tally + 1

and here’s #at:put: where the exception is signaled:

at: index put: value
        <primitive: 61>
        index isInteger ifTrue:
                [self class isVariable
                        ifTrue: [(index >= 1 and: [index <= self size])
                                        ifTrue: [self errorImproperStore]
                                        ifFalse: [self errorSubscriptBounds: index]] <——— signaled
                        ifFalse: [self errorNotIndexable]].
        index isNumber
                ifTrue: [^self at: index asInteger put: value]
                ifFalse: [self errorNonIntegerIndex]

Here’s the weird thing: according to the debugger ‘array' in #noCheckAdd: IS NOT THE SAME INSTANCE as ‘self’ in #at:put:!!!!!! ????????? When I look at the pointers to both arrays, the correct one is pointed to by the dictionary while the other is only being referenced by the exception context:

Bad array:
1: SubscriptOutOfBounds: 88
2: Array(Object)>>errorSubscriptBounds:
3: Array(Object>>at:put:
4: an Inspector
…

Good array:
1: aCBConfiguration(size 107)


I really have no clue how this could have happened. I’d appreciate any thoughts you might have…

Cheers,
Max



--
best,
Eliot
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