On Wed, Oct 17, 2012 at 9:07 AM, Dmitry Vyal
<akamaus@gmail.com> wrote:
Hello anyone
I've written a snippet which generates a file full of random strings. When compiled with -O2 on ghc-7.6, the generation speed is about 2Mb per second which is on par with interpreted php. That's the fact I find rather disappointing. Maybe I've missed something trivial? Any suggestions and explanations are welcome. :)
% cat ext_sort.hs
import qualified Data.Text as T
import System.Random
import Control.Exception
import Control.Monad
import System.IO
import qualified Data.Text.IO as TI
gen_string g = let (len, g') = randomR (50, 450) g
in T.unfoldrN len rand_text (len, g')
where rand_text (0,_) = Nothing
rand_text (k,g) = let (c, g') = randomR ('a','z') g
in Just (c, ((k-1), g'))
write_corpus file = bracket (openFile file WriteMode) hClose $ \h -> do
let size = 100000
sequence $ replicate size $ do
g <- newStdGen
let text = gen_string g
TI.hPutStrLn h text
main = do
putStrLn "generating text corpus"
write_corpus "test.txt"
% cat ext_sort.prof
Wed Oct 17 10:59 2012 Time and Allocation Profiling Report (Final)
ext_sort +RTS -p -RTS
total time = 32.56 secs (32558 ticks @ 1000 us, 1 processor)
total alloc = 12,742,917,332 bytes (excludes profiling overheads)
COST CENTRE MODULE %time %alloc
gen_string.rand_text.(...) Main 70.7 69.8
gen_string Main 17.6 15.8
gen_string.rand_text Main 5.4 13.3
write_corpus.\ Main 4.3 0.8
individual inherited
COST CENTRE MODULE no. entries %time %alloc %time %alloc
MAIN MAIN 67 0 0.0 0.0 100.0 100.0
main Main 135 0 0.0 0.0 100.0 100.0
write_corpus Main 137 0 0.0 0.0 100.0 100.0
write_corpus.\ Main 138 1 4.3 0.8 100.0 100.0
write_corpus.\.text Main 140 100000 0.0 0.0 95.7 99.2
gen_string Main 141 100000 17.6 15.8 95.7 99.2
gen_string.g' Main 147 100000 0.0 0.0 0.0 0.0
gen_string.rand_text Main 144 25109743 5.4 13.3 77.5 83.2
gen_string.rand_text.g' Main 148 24909743 0.6 0.0 0.6 0.0
gen_string.rand_text.(...) Main 146 25009743 70.7 69.8 70.7 69.8
gen_string.rand_text.c Main 145 25009743 0.8 0.0 0.8 0.0
gen_string.len Main 143 100000 0.0 0.0 0.0 0.0
gen_string.(...) Main 142 100000 0.6 0.3 0.6 0.3
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