[Pharo-project] Preallocation behavior

Henrik Sperre Johansen henrik.s.johansen at veloxit.no
Thu Apr 28 12:17:15 CEST 2011


On 28.04.2011 10:49, Stéphane Ducasse wrote:
> Henrik
>
> you lost me
>
>> In the first example, you are making a single string with all A's of size 9000 repeated 500 times.
>> In the second example, you are making 9000 strings with all A's of size 10000  repeated 500 times.
> Why?
My bad, I misread and thought the code was using atAllPut: , like it 
should :) (that is, if its intent is to initialize a presized collection 
with default values)

MessageTally spyOn:

  [ 500 timesRepeat: [
  | str |
  str :=String new: 9000.
  str atAllPut: $A ]].

only takes a couple of milliseconds.


As for nextPut: vs nextPutAll:, that is to be expected.
nextPutAll: is optimized for sizes>  1, on my machine it "catches up" when you surpass 4 characters added in each loop.

Cheers,
Henry







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