Hi All, Can someone who encounters the performance problems mentioned in this thread please try out the following code snippets and report on the outcome?!
First try in a workspace: | lookupLengths | lookupLengths _ SortedCollection new. Behavior allSubInstancesDo:[:class | | md | md _ class methodDict. lookupLengths addAll:(md keys asSortedCollection collect:[:sel | (((md scanFor: sel) - sel identityHash) \ md basicSize) -> (class -> sel)]) ]. lookupLengths asBag sortedCounts inspect. lookupLenghts last:100 inspect.
This will give you two inspectors. The first will show the sorted counts of a bag which entries should be interpreted the following: #occurences -> #lookupLength -> sampleClass -> sampleSelector Please report on the differences between a slow image and an acceptable image (preferrably on the same system) The second will give you the details of the 100 Methods with the highest lookupLenghts. Please look swiftly over this list if you can detect any Morphic specific selectors with long lookup lenghts.
The second thing i want you to try is to grow all your MethodDictionaries that have exessive lookupLenghts. The following code snippet will do this for you.
| lookupLengths | Behavior allSubInstancesDo:[:class | | md | md _ class methodDict. md isEmpty ifFalse:[ lookupLengths _ SortedCollection new. lookupLengths addAll:(md keys asSortedCollection collect:[:sel | (((md scanFor: sel) - sel identityHash) \ md basicSize) -> (class -> sel)]). (lookupLengths last key > 9) ifTrue:[md grow]]]
Please report if your image "feels" any swifter after this operation. Note#0: Be sure not to have any PackagePaneBrowser (aka 5-pane browser) open when you do your tests because these beasts will stop all morphic updating (and maybe event dispatch) for up to one second every second on a slow machine. This is due to a design bug which can very easily be avoided using a changeset i once posted to the list but don't have the patience to dig up right now. Note#1: These operations might take a _very_ long time (especially on a slow system) so be pationent) (on my 1700+ it was in the second range but since you're especially encountering problems on slow systems you will probably do the tests there, too -- so don't say i didn't warn you ). Note#2: LookupLenghts stand for the amount of probes the vm has to do in _a single method dictionary_ to find a method corresponding to a selector. This is just a minimum measure because it doesn't count the number of probes spent while following the superclass chain. These numbers are typically small for almost empty method dictionaries but may become huge when all superclasses have long probe chains and the selector is only implemented in ProtoObject Note#3: It is nowhere near guranteed that this will change anything because lookup lenghts aren't _supposed_ to make a difference. It is widely believed that the vm's lookup cache mechanism should deal with the performance hit that would result from long probe chains. I have, whatsoever, two strong hints that lookupLenghts _might_ be part of the problem you encounter. These are: Hint#1: The problem has arisen rather gradually and noone has yet been able to find any particular change that made the difference hint#2: The Lookup cache (as i understand it) seems to be rather small for as big a system as morphic (i only saw space for 512 entries last time i looked) and gets flushed on several accasions (such as gc's).
Looking forward to your feedback, Torge