On 25 January 2005 23:27, S. Alexander Jacobson wrote:
Oops. It pays to check your checking code before making posts like this.
After actually running the correct test, I am still getting semi-ridiculous space behavior (6k/pair)!
import qualified Map zipped =zip [1..] [1..100000]::[(Int,Int)] untup f (x,y) = f x y produce = foldr (untup Map.insert) Map.empty zipped fm = length $ Map.keys produce main = print $ fm
Has this profile:
example +RTS -p -K5M -RTS
total time = 5.10 secs (255 ticks @ 20 ms) total alloc = 612,534,236 bytes (excludes profiling overheads)
COST CENTRE MODULE %time %alloc balance Map 71.8 72.8 insert Map 12.2 10.8 size Map 9.0 9.7 bin Map 2.4 2.2 rotateR Map 1.6 0.3 zipped Main 0.8 1.9
Notice the 612Mb for storing a mapping from Int to Int!!
Notice that's 612Mb *allocation* to create the finite map and deconstruct it into a list. Not 612Mb of live heap to store the finite map. If you make sure everything is evaluated, and examine the heap profile I'm sure you'll find that the finite map is taking a reasonable amount of space (perhaps 20-30 bytes per node for storing integers, I guess). To get a rough idea of the total live heap without profiling, you can run the program with +RTS -sstderr and look at the memory "in use" figure. Cheers, Simon