Andreas Klebinger pushed to branch wip/andreask/hadrian_build_par at Glasgow Haskell Compiler / GHC Commits: b65ce27c by Andreas Klebinger at 2026-02-19T09:27:54+01:00 hadrian/build-cabal: Better respect and utilize -j * We now respect -j<n> for the cabal invocation to build hadrian rather than hardcoding -j * We use the --semaphore flag to ensure cabal/ghc build the hadrian executable in parallel using the -jsem mechanism. Saves 10-15s on fresh builds for me. Fixes #26876 - - - - - 1 changed file: - hadrian/build-cabal Changes: ===================================== hadrian/build-cabal ===================================== @@ -23,9 +23,52 @@ fi CABVERSTR=$("$CABAL" --numeric-version) CABVER=( ${CABVERSTR//./ } ) +THREADS="-j1" +GC_THREADS="" +SEMAPHORE="" + +echo "$@" + +# Try building hadrian in parallel. We check for -j<n>. +# If threads > 1 we pass --semaphore to allow ghc to build more than one module in parallel +# If threads > 4 we pass -qn as higher parallel gc thread counts can lead to slow downs +# We only do any of thise for cabal >= 3.14, because I don't trust older versions to handle --semaphore right +if [ "${CABVER[0]}" -gt 3 ] || [ "${CABVER[0]}" -eq 3 -a "${CABVER[1]}" -ge 14 ]; +then + + for arg in "$@"; do + case "$arg" in + -j) + GC_THREADS="-qn4" + SEMAPHORE="--semaphore" + THREADS="-j" + ;; + -j[0-9]*) + threads="${arg#-j}" + if [[ "$threads" =~ ^[0-9]+$ ]] && [ "$threads" -ne 0 ]; then + THREADS="-j${threads}" + if [ $threads -ge 4 ]; then + GC_THREADS="-qn4" + fi + if [ $threads -gt 1 ]; then + SEMAPHORE="--semaphore" + fi + fi + ;; + esac + + done + +fi + +if [ "$(uname -s)" = "FreeBSD" ]; then + # Can't rely on posix semaphore support in free bsd. + SEMAPHORE="" +fi + if [ "${CABVER[0]}" -gt 2 -o "${CABVER[0]}" -eq 2 -a "${CABVER[1]}" -ge 2 ]; then - "$CABAL" --project-file="$PROJ" new-build "${CABFLAGS[@]}" -j exe:hadrian + "$CABAL" --project-file="$PROJ" new-build "${CABFLAGS[@]}" ${THREADS} ${SEMAPHORE} --ghc-options="+RTS ${GC_THREADS} -RTS" exe:hadrian # use new-exec instead of new-run to make sure that the build-tools (alex & happy) are in PATH "$CABAL" --project-file="$PROJ" new-exec "${CABFLAGS[@]}" hadrian -- \ --directory "$PWD" \ View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b65ce27c0b28e5853535b6c3944a62b3... -- View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/b65ce27c0b28e5853535b6c3944a62b3... You're receiving this email because of your account on gitlab.haskell.org.