How weak finalization affects the performance
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How weak finalization affects the performance
 
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Here the idea, which came to Chris,
put a delay into #finalizationProcess loop: finalizationProcess [true] whileTrue: [ WeakFinalizationList initTestPair. FinalizationSemaphore wait. FinalizationLock critical: [ WeakFinalizationList checkTestPair. FinalizationDependents do: [:weakDependent | weakDependent ifNotNil: [weakDependent finalizeValues]]] ifError: [:msg :rcvr | rcvr error: msg]. 5 seconds asDelay wait. ]. And here a simple benchmark, which triggers GC often: [ Array new: 100 ] bench without delay: '2,450,000 per second.' '2,490,000 per second.' '2,490,000 per second.' '2,480,000 per second.' '2,530,000 per second.' with delay: '2,670,000 per second.' '2,680,000 per second.' '2,690,000 per second.' '2,730,000 per second.' roughly about ~8% faster :) But now lets put something big into weak array: | dict b | dict := WeakKeyDictionary new addAll: (( 1 to: 1000 ) collect: [:i | i->i] ); yourself. WeakArray addWeakDependent: dict. b := [ Array new: 100 ] bench. WeakArray removeWeakDependent: dict. b without delay: '1,840,000 per second.' '2,060,000 per second.' '2,130,000 per second.' with delay: '3,030,000 per second.' '2,880,000 per second.' '2,890,000 per second.' Do not forget to do: WeakArray restartFinalizationProcess when you changing the #finalizationProcess method, otherwise you won't see real numbers. So, i like the idea of putting delay there. Finalization is eventual, and there is no hard guarantees that it will happen in micro-second just after some object become garbage. So, be it 5 seconds or 1000 seconds not really matters. What is matters that with delay we win much more, by avoiding wasting time in finalization process too often. -- Best regards, Igor Stasenko AKA sig. _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
Re: [squeak-dev] How weak finalization affects the performance
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On 26 October 2010 10:30, Andres Valloud
<[hidden email]> wrote: > Why does finalization do any work when running a block which I think just > creates garbage? Is finalization on a per class basis (i.e.: the VM > notifies the image that some objects might be notified, and the image just > enumerates through them), or on a per object basis (i.e.: the VM maintains a > finalization queue as in VisualWorks)? > There is no per-object or per-class finalization in Squeak. One must either register an object using WeakRegistry, or add own object to weak dependents (it should answer to #finalizeValues). Squeak VM signals the semaphore each time GC happen, and actually, a finalization process could do something arbitrary to react on such event. Putting delay there ensuring that even if you put a very ineffective finalization into weak dependents, it won't affect the performance too much. > On 10/26/10 0:25 , Igor Stasenko wrote: >> >> Here the idea, which came to Chris, >> put a delay into #finalizationProcess loop: >> >> finalizationProcess >> [true] whileTrue: >> [ WeakFinalizationList initTestPair. >> FinalizationSemaphore wait. >> FinalizationLock critical: >> [ >> WeakFinalizationList checkTestPair. >> FinalizationDependents do: >> [:weakDependent | >> weakDependent ifNotNil: >> [weakDependent finalizeValues]]] >> ifError: >> [:msg :rcvr | rcvr error: msg]. >> 5 seconds asDelay wait. >> ]. >> >> >> And here a simple benchmark, which triggers GC often: >> >> [ Array new: 100 ] bench >> >> without delay: >> >> '2,450,000 per second.' >> '2,490,000 per second.' >> '2,490,000 per second.' >> '2,480,000 per second.' >> '2,530,000 per second.' >> >> with delay: >> >> '2,670,000 per second.' >> '2,680,000 per second.' >> '2,690,000 per second.' >> '2,730,000 per second.' >> >> roughly about ~8% faster :) >> >> But now lets put something big into weak array: >> >> | dict b | >> dict := WeakKeyDictionary new addAll: (( 1 to: 1000 ) collect: [:i | >> i->i] ); yourself. >> WeakArray addWeakDependent: dict. >> b := [ Array new: 100 ] bench. >> WeakArray removeWeakDependent: dict. >> b >> >> without delay: >> >> '1,840,000 per second.' >> '2,060,000 per second.' >> '2,130,000 per second.' >> >> with delay: >> >> '3,030,000 per second.' >> '2,880,000 per second.' >> '2,890,000 per second.' >> >> Do not forget to do: >> WeakArray restartFinalizationProcess >> >> when you changing the #finalizationProcess method, >> otherwise you won't see real numbers. >> >> So, i like the idea of putting delay there. >> Finalization is eventual, and there is no hard guarantees that it will >> happen in micro-second just after some object become garbage. >> So, be it 5 seconds or 1000 seconds not really matters. >> What is matters that with delay we win much more, by avoiding wasting >> time in finalization process too often. >> >> > > -- Best regards, Igor Stasenko AKA sig. _______________________________________________ Pharo-project mailing list [hidden email] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project |
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