Re: [Pharo-project] SparseLargeTable instances and Unicode

Sept. 21, 2010

      On Tue, Sep 21, 2010 at 7:55 PM, Henrik Sperre Johansen <
henrik.s.johansen@veloxit.no> wrote:
...
On 21.09.2010 19:10, Mariano Martinez Peck wrote:
...
Hi folks. I wasn't aware of the class SparseLargeTable but it seems it has
two important instances "SparseLargeTable allInstances size -> 2"
They are the class side variables #DecimalProperty and #GeneralCategory in
Unicode.
Actually,
(Unicode classPool at: 'GeneralCategory') size  -> 917632
(Unicode classPool at: 'DecimalProperty') size -> 917632
So...collections of almost 1 million elements.
Now a couple of questions:
1) Is this normal/expected?   In my calculus both arrays are like 3mb of
memory
Look at the implementation, there's a reason they're called sparse.
If my math is correct (crosses fingers), DecimalProperty is ~15KB,
GeneralCategory ~70KB
So...there must be a problem with my code, I was doing something like
SpaceTally does:

spaceForUsedInstancesOf: aClass withInstanceCount: instCount
    "Answer the number of bytes consumed by all instances of the given
class, including their object headers."

    | isCompact instVarBytes bytesPerElement headerBytes total |
    instCount = 0 ifTrue: [^ 0].
    isCompact := aClass indexIfCompact > 0.
    instVarBytes := aClass instSize * 4.
    aClass isVariable
        ifTrue: [
            bytesPerElement := aClass isBytes ifTrue: [1] ifFalse: [4].
            total := 0.
            aClass allInstancesDo: [:inst | | contentBytes |
                contentBytes := instVarBytes + (inst size *
bytesPerElement).
                headerBytes :=
                    contentBytes > 255
                        ifTrue: [12]
                        ifFalse: [isCompact ifTrue: [4] ifFalse: [8]].
                    (UnusedObjectDiscoverer current primitiveGetUsedBit:
inst) ifTrue:
                [total := total + headerBytes + contentBytes]].
            ^ total]
        ifFalse: [
            headerBytes :=
                instVarBytes > 255
                    ifTrue: [12]
                    ifFalse: [isCompact ifTrue: [4] ifFalse: [8]].
            ^ instCount * (headerBytes + instVarBytes)].

SparseLargeTable instanceCount ->>> 2

SpaceTally new spaceForUsedInstancesOf: SparseLargeTable withInstanceCount:
2   ->>>  7341112

thanks
...
...
2) If I don't use UTF and I send an encoding as parameter in the VM
(different from UTF), do I need this class side variables?
What Lukas said.
Cheers,
Henry
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