Hi. I profiled a bit and found problem:
PharoClassInstaller>>migrateClasses: old to: new using: anInstanceModification instanceModification := anInstanceModification. old ifEmpty: [ ^ self ]. [ 1 to: old size do: [ :index | self updateClass: (old at: index) to: (new at: index)]. old elementsForwardIdentityTo: new. " Garbage collect away the zombie instances left behind in garbage memory in #updateInstancesFrom: " " If we don't clean up this garbage, a second update would revive them with a wrong layout! " " (newClass rather than oldClass, since they are now both newClass) " Smalltalk garbageCollect. ] valueUnpreemptively Commenting garbage collection here increases performance 10 times. Then commenting class update loop increases performance 3 times more. But this loop is required. It adopts all instances of old class to new one. And time here spent in #allInstances method. Can we remove manual garbage collection here? Why it is needed? 2017-04-12 9:34 GMT+02:00 Peter Uhnak <i.uh...@gmail.com>: > Hi, > > does anyone know why adding instance variables is so slow? > > I did some quick benchmarks (see below), resulting in more than order of > magnitude speed difference between having it in the class definition and > adding it later. > > In fact it is still much faster to delete the class and then recreate it > with the instance variables in the d efinition. For four arguments it is > till 8x faster to delete the class four times and recreate it then just add > the variable. Unfortunately I cannot just trash the classes (they have > methods and inheritance). > > So the question is: why is it so slow? can I somehow improve the > performance? > > Thanks, > Peter > > > Benchmarks: > > > [ > cls := Object subclass: #Some1. > cls removeFromSystem. > ] bench. "'91 per second'" > > [ > cls := Object subclass: #Some2 instanceVariableNames: 'variable'. > cls removeFromSystem > ] bench. "'90 per second'" > > [ > cls := Object subclass: #Some3. > cls addInstVarNamed: 'variable'. > cls removeFromSystem. > ] bench. "'7 per second'" > > [ > cls := Object subclass: #Some4. > cls removeFromSystem. > cls := Object subclass: #Some4 instanceVariableNames: 'variable'. > cls removeFromSystem. > ] bench. "'43 per second'" > > > > > [ > cls := Object subclass: #Some3. > cls addInstVarNamed: 'variable1'. > cls addInstVarNamed: 'variable2'. > cls addInstVarNamed: 'variable3'. > cls addInstVarNamed: 'variable4'. > cls removeFromSystem. > ] bench. "'2 per second'" > > [ > cls := Object subclass: #Some4. > cls removeFromSystem. > cls := Object subclass: #Some4 instanceVariableNames: 'variable1 > variable2 variable3 variable4'. > cls removeFromSystem. > ] bench. "'44 per second'" > > [ > cls := Object subclass: #Some5. > cls removeFromSystem. > cls := Object subclass: #Some5 instanceVariableNames: 'variable1'. > cls removeFromSystem. > cls := Object subclass: #Some5 instanceVariableNames: 'variable1 > variable2'. > cls removeFromSystem. > cls := Object subclass: #Some5 instanceVariableNames: 'variable1 > variable2 variable3'. > cls removeFromSystem. > cls := Object subclass: #Some5 instanceVariableNames: 'variable1 > variable2 variable3 variable4'. > cls removeFromSystem. > ] bench. "'17.269 per second'" > >
