Skip to content

Performance regression in ghcid

Summary

I use ghcid to run my tests, whenever I make a change, the delay between displaying "Running test..." and the beginning of the execution is much slower in GHC 9.4.3 (few seconds) than in 9.2.5 (almost instantaneously).

Steps to reproduce

  • Clone the repository
  • Run ghcid --command='cabal v2-repl bug' -W -T End.dbg
  • Change src/M10.hs for example
  • Toggle between ghc943 and ghc925 in flake.nix

Expected behavior

It shouldn't be that slow.

Environment

  • GHC version used: 9.2.5 vs 9.4.3

Optional:

  • Operating System: NixOS unstable
  • System Architecture: x86_64
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information