profiling confusion

_Profiling_trouble.md

The profile graphs shows empty :(

 $(cabal list-bin exe:arrayx) +RTS -h -p -N -RTS

RTS options to produce runtime statistics

 $(cabal list-bin exe:arrayx) +RTS -s -RTS     

-T collects the data but produces no output -t produces a single line of output in the same format as GHC’s -Rghc-timing option, -s produces a more detailed summary at the end of the program, and -S additionally produces information about each and every garbage collection.

If you use the -T flag then, you should access the statistics using GHC.Stats.

GHC.Stats

System.Mem.performGC

The GHC Runtime System

arrayx.cabal

cabal-version: 3.4
name: arrayx
version: 0.1.0.0

executable arrayx
    main-is: Main.hs
    ghc-options: -threaded
    build-depends:
        base,
        array
    default-language: Haskell2010

cabal.project

packages: ./*.cabal
profiling: True
package arrayx
    profiling-detail: all-functions

Main.hs

{-# LANGUAGE NumDecimals, BangPatterns #-}
module Main where

import Data.Array
import Control.Concurrent
import System.Mem

type A = Array Integer Integer

{-# NOINLINE makea #-}
makea :: Integer -> IO A
makea i = do 
        let !z = array (1, i) (do
                        v <- [1..i]
                        pure (v,v))
         in pure z

-- https://tech.channable.com/posts/2020-04-07-lessons-in-managing-haskell-memory.html
-- https://ro-che.info/articles/2020-05-14-visualize-haskell-heap-profiles
-- https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/profiling.html

{-# NOINLINE foo #-}
foo :: A -> IO ()
foo _ = do
    performGC 
    threadDelay 10e6
    pure ()

main :: IO ()
main = do
    !arr <- makea 100000
    performGC 
    threadDelay 10e6
    foo arr