[Moose-dev] A quick analyzis of the usage of instance variables in Moose

Hi Moose users, as you may know, at Synectique we experiment lots of issues about memory usage. That's why i had a look at the number of unused instance variables in one of our system loaded with a big model from one of our main customer. Total instance variables: 26.852.653 Used instance variables: 17.393.938 Empty collections: 5.023.508 Recoverable instance variables: 14.482.223 The recoverable instance variables are those with nil or an empty collection (or MultiValueLink) As you can see, we can save a lot of memory :-) Here is my (dirty) code to get that: countUsedInstanceVariableInForSubInstances: aClass | usedInstNbr instNbr emptyCollNbr | usedInstNbr := 0. instNbr := 0. emptyCollNbr := 0. aClass allSubInstancesDo: [ :anEntity | instNbr := instNbr + anEntity class allInstVarNames size. anEntity class allInstVarNames doWithIndex: [ :e :i | (anEntity instVarAt: i) ifNotNil: [ :content | ([ content isEmpty. emptyCollNbr := emptyCollNbr + 1. false ] on: MessageNotUnderstood do: [ false ]) ifFalse: [ usedInstNbr := usedInstNbr + 1 ] ] ] ]. ^ {('Used instance variables' -> usedInstNbr). ('empty collections' -> emptyCollNbr). ('Recoverable instance variables' -> (instNbr - (usedInstNbr - emptyCollNbr))). ('Total instance variables' -> instNbr)} -- *Guillaume Larcheveque*