Begin forwarded message:
From: Camillo Bruni <camillobruni@gmail.com> Subject: Re: [Pharo-fuel] (Identity)Dictionary benchmarks Date: 21. Mai 2013 10:58:29 MESZ To: The Fuel Project <pharo-fuel@lists.gforge.inria.fr> Reply-To: The Fuel Project <pharo-fuel@lists.gforge.inria.fr>
my random pessimistic comments
a) your benchmarking script sucks! => use SMARK!! http://smalltalkhub.com/#!/~StefanMarr/SMark b) check my master thesis for a more thorough testing of dictionary, including a cleaner implementation that defaults to something like a small dictionary without a special class: http://scg.unibe.ch/archive/masters/Brun11a.pdf
the optimistic version:
On 2013-05-21, at 09:47, Max Leske <m.leske@netstyle.ch> wrote:
My coworker performed some interesting benchmarks on the various dictionary types in Pharo. If you look at the attachments you'll see four things: 1. SmallDictionary and SmallIdentityDictionary are totally useless when it comes to performance. Unless their existence is somehow justified by saving space (which might be important for embedded systems) I don't see why we should keep them around.
yes their usage is not always justified, but be careful what you measure: as far as I see you only measure addition, no? (sorry again, but that benchmark brutally sucks, it's so damn hard to read... :P). Iteration and retrieval have to measure as well, also how the dictionaries behave under key hash collisions (though I am definitely not defending the small dicts.. :).
2. The special Fuel collections for large numbers of elements could be a valuable addition to the basic collections
THere is the pluggable key dictionary for that reason already, no? The main problem is the limited hashes which results in quite some hash collisions for very large dictionaries.
3. SmallInteger>>identityHash is really slow. Using SmallInteger as keys in IdentityDictionary is significantly slower than using them in a regular Dictionary because the identity check is done via #identityHash (#hash simply answers self).
that is really strange :/
4. Arrays are cool :)
Should I open issues on FogBugz for any of these points? Especially point 3 bothers me because I feel that using a "primitive" type should be fast under all circumstances.
You'll find below the benchmark data (collected in 1.4, verified in 2.0) and the code to run it.
Cheers, Max
<performance.xlsx>
<performance.xls>
--------------------------------------------------------------
( comments are variations)
sizes := #( 10 20 30 40 50 60 70 80 90 100 120 130 140 150 160 170 180 190 200 300 400 500 600 700 800 900 1000 ). "sizes := #( 10 20 30 40 50 60 70 80 90 100 120 130 140 150 160 170 180 190 200 300 400 500 600 700 800 900 1000 1500 2000 2500 3000 3500 4000 4500 5000 6000 7000 8000 9000 10000 )." "batches := sizes collect: [ :size | size -> ((10000000 / size) asFloat // 10) ]." batches := sizes collect: [ :size | size -> 10000 ]. alphabet := Character alphabet.
batches do: [ :a | Transcript tab; show: a key asString ]. Transcript cr. batches do: [ :a | Transcript tab; show: a value asString ]. Transcript cr. "{ Dictionary. SmallDictionary. IdentityDictionary. SmallIdentityDictionary. FLLargeIdentityDictionary } " { Dictionary. IdentityDictionary. FLLargeIdentityDictionary } "{ Array }" do: [ :class | Smalltalk garbageCollect. Transcript show: class name. batches do: [ :a | | struct strings iterations | "strings := (1 to: a key) collect: [ :i | i asString ]." strings := (1 to: a key) collect: [ :i | String streamContents: [ :s | 20 atRandom timesRepeat: [ s nextPut: alphabet atRandom ] ] ]. struct := class new. "struct := (class = FLLargeIdentityDictionary ifTrue: [ class new ] ifFalse: [ class new: a key ])." Transcript tab; show: ([ a value timesRepeat: [ 1 to: a key do: [ :i | struct at: (strings at: i)" i" put: i ] ] ] timeToRun). strings := nil ] displayingProgress: class name asString. Transcript cr. ] displayingProgress: 'Processing ...'
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