ci: add cmake --parallel build option #353

pull ryanofsky wants to merge 1 commits into bitcoin-core:master from ryanofsky:pr/cmake-parallel changing 2 files +3 −4

ryanofsky commented at 8:38 PM on August 20, 2026: collaborator

Drop nproc call and inconsistent -j setting.
ci: add cmake --parallel build option
Drop nproc call and inconsistent -j setting.
eac91e08f4
DrahtBot commented at 8:38 PM on August 20, 2026: none


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Conflicts

Reviewers, this pull request conflicts with the following ones:
- #352 (ci: add cmake debug output by ryanofsky)
- #212 (ci: add newdeps job testing newer versions of cmake and capnproto by ryanofsky)
- #209 (cmake: Increase cmake policy version by ryanofsky)
- #175 (Set cmake_minimum_required(VERSION 3.22) by maflcko)
If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

in ci/scripts/ci.sh:29 in eac91e08f4

  23 | @@ -24,15 +24,14 @@ ver_ge() { [ "$(printf '%s\n' "$2" "$1" | sort -V | head -n1)" = "$2" ]; }
  24 |  src_dir=$PWD
  25 |  mkdir -p "$CI_DIR"
  26 |  cd "$CI_DIR"
  27 | -export CMAKE_BUILD_PARALLEL_LEVEL="$(nproc)"
  28 |  cmake "$src_dir" "${CMAKE_ARGS[@]+"${CMAKE_ARGS[@]}"}"
  29 |  if ver_ge "$cmake_ver" "3.15"; then
  30 | -  cmake --build . -t "${BUILD_TARGETS[@]}" -- "${BUILD_ARGS[@]+"${BUILD_ARGS[@]}"}"
  31 | +  cmake --build . --parallel -t "${BUILD_TARGETS[@]}" -- "${BUILD_ARGS[@]+"${BUILD_ARGS[@]}"}"

hebasto commented at 10:35 AM on August 23, 2026:

From the CMake docs:

If <jobs> is omitted the native build tool’s default number is used.

I don't think this change is an improvement, as it might reduce build parallelism.

maflcko commented at 7:16 AM on August 24, 2026:

It could also lead to over-parallelism and lead to OOM?

ryanofsky commented at 3:05 AM on August 26, 2026: collaborator

Good points! Closing this PR as I did not know --parallel had this crazy behavior. For a followup though it could still be good to drop -j4 from sanitize.bash
ryanofsky closed this on Aug 26, 2026

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ci: add cmake --parallel build option #353

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