gistfile1.hs

-- | Spawn N threads, each one adding new elements to sets randomly
-- selected from a pool of sets.
module Main where

import           Control.Concurrent
import           Control.DeepSeq
import           Control.Monad
import           Data.IORef
import           Data.Maybe
import qualified Data.Set            as S
import           Options.Applicative
import           System.Random

main = do
    threads <- execParser cmdOpts
    setPool <- replicateM threads $ newIORef (S.empty, 0)
    replicateM threads $ forkIO (buildSet setPool threads >> return ())
    threadDelay 10000000 -- run for 10 seconds
    return ()

cmdOpts :: ParserInfo Int
cmdOpts = info (helper <*> argParser) mempty

argParser :: Parser Int
argParser = argument auto (help "Amount of threads to spawn" <> metavar "THREADS")

buildSet :: [IORef (S.Set Int, Int)] -> Int -> IO (S.Set Int, Int)
buildSet setPool len = do
    setRef <- (setPool !!) <$> randomRIO (0, len - 1)
    atomicModifyIORef' setRef $ \(set, lastElem) -> ((S.insert (lastElem + 1) set, lastElem + 1), ())
    buildSet setPool len

gistfile2.txt

./dist/dist-sandbox-e53dad53/build/random-parallel-snowball/random-parallel-snowball 1 +RTS -N -l -qa -srandom-parallel-snowball_1_qa.gc 
  15,880,207,640 bytes allocated in the heap
   4,084,408,656 bytes copied during GC
     992,608,224 bytes maximum residency (13 sample(s))
      15,831,072 bytes maximum slop
            1958 MB total memory in use (0 MB lost due to fragmentation)

                                     Tot time (elapsed)  Avg pause  Max pause
  Gen  0     30757 colls, 30757 par   19.118s   2.414s     0.0001s    0.0144s
  Gen  1        13 colls,    12 par   29.684s   3.856s     0.2966s    1.8202s

  Parallel GC work balance: 0.00% (serial 0%, perfect 100%)

  TASKS: 18 (1 bound, 17 peak workers (17 total), using -N8)

  SPARKS: 0 (0 converted, 0 overflowed, 0 dud, 0 GC'd, 0 fizzled)

  INIT    time    0.015s  (  0.014s elapsed)
  MUT     time    8.823s  (  4.534s elapsed)
  GC      time   48.803s  (  6.271s elapsed)
  EXIT    time    0.100s  (  0.099s elapsed)
  Total   time   57.742s  ( 10.918s elapsed)

  Alloc rate    1,799,875,628 bytes per MUT second

  Productivity  15.5% of total user, 81.7% of total elapsed

gc_alloc_block_sync: 457978
whitehole_spin: 0
gen[0].sync: 22
gen[1].sync: 189