From 04af5dfdef93817930b3ddd239c762543198044e Mon Sep 17 00:00:00 2001
From: Lucas Colley <lucas.colley8@gmail.com>
Date: Tue, 17 Jun 2025 00:43:54 +0100
Subject: [PATCH 1/2] DEV: parallel workers task args

---
 pixi.toml | 40 ++++++++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 12 deletions(-)

diff --git a/pixi.toml b/pixi.toml
index 3782888..e3f14f1 100644
--- a/pixi.toml
+++ b/pixi.toml
@@ -28,12 +28,14 @@ cwd = "."
 
 [feature.build.tasks.build-only]
 # Just build without configure
-cmd = ["cmake", "--build", "build", "--config", "Release"]
+cmd = ["cmake", "--build", "build", "--config", "Release", "-j{{ parallel }}"]
 cwd = "."
+args = [{ arg = "parallel", default = "2" }]
 
 [feature.build.tasks.build]
 # Build with default configuration
-depends-on = ["configure", "build-only"]
+depends-on = ["configure", { "task" = "build-only", "args" = ["{{ parallel }}"] }]
+args = [{ arg = "parallel", default = "2" }]
 
 ## Tests
 
@@ -60,11 +62,22 @@ configure-tests.cmd = [
 ]
 configure-tests.cwd = "."
 # build for tests
-build-tests.depends-on = ["configure-tests", "build-only"]
-# run tests
-tests.cmd = ["ctest", "--output-on-failure", "--test-dir", "build/tests"]
-tests.depends-on = ["clone-xsref", "build-tests"]
-tests.cwd = "."
+build-tests.depends-on = [
+  "configure-tests",
+  { "task" = "build-only", "args" = ["{{ parallel }}"] },
+]
+build-tests.args = [{ arg = "parallel", default = "2" }]
+# just run tests
+tests-only.cmd = ["ctest", "--output-on-failure", "--test-dir", "build/tests", "-j{{ parallel }}"]
+tests-only.cwd = "."
+tests-only.args = [{ arg = "parallel", default = "2" }]
+# build and run tests
+tests.depends-on = [
+  "clone-xsref",
+  { "task" = "build-tests", "args" = ["{{ parallel }}"] },
+  { "task" = "tests-only", args = ["{{ parallel }}"] },
+]
+tests.args = [{ arg = "parallel", default = "2" }]
 
 ## clang-format
 
@@ -109,13 +122,15 @@ ccache = ">=4.11.2,<5"
 [feature.tests-ci.tasks]
 # Build and generate coverage report
 # TODO: use a task arg for parallelism https://github.com/prefix-dev/pixi/pull/3433
-build-tests-ci.cmd = ["cmake", "--build", "build", "-j3", "--config", "Release"]
+build-tests-ci.cmd = ["cmake", "--build", "build", "-j{{ parallel }}", "--config", "Release"]
 build-tests-ci.depends-on = ["clone-xsref", "configure-coverage"]
 build-tests-ci.cwd = "."
+build-tests-ci.args = [{ arg = "parallel", default = "2" }]
 # Run tests
-tests-ci.cmd = ["ctest", "--output-on-failure", "--test-dir", "build/tests", "-j3"]
-tests-ci.depends-on = ["build-tests-ci"]
+tests-ci.cmd = ["ctest", "--output-on-failure", "--test-dir", "build/tests", "-j{{ parallel }}"]
+tests-ci.depends-on = [{ "task" = "build-tests-ci", "args" = ["{{ parallel }}"] }]
 tests-ci.cwd = "."
+tests-ci.args = [{ arg = "parallel", default = "2" }]
 # Coverage
 coverage.cmd = [
   "cmake",
@@ -123,12 +138,13 @@ coverage.cmd = [
   "build",
   "--target",
   "coverage_html",
-  "-j3",
+  "-j{{ parallel }}",
   "--config",
   "Release",
 ]
-coverage.depends-on = ["tests-ci"]
+coverage.depends-on = [{ "task" = "tests-ci", "args" = ["{{ parallel }}"] }]
 coverage.cwd = "."
+coverage.args = [{ arg = "parallel", default = "2" }]
 
 # CuPy tests
 [feature.cupy-tests]

From 9aa446f211a1cb0300834d319f8c71c7279abe5e Mon Sep 17 00:00:00 2001
From: Lucas Colley <lucas.colley8@gmail.com>
Date: Tue, 17 Jun 2025 00:53:01 +0100
Subject: [PATCH 2/2] CI: set NUM_WORKERS

---
 .github/workflows/tests.yml | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 11e7b6c..2cfd0ca 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -26,7 +26,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       - uses: prefix-dev/setup-pixi@92815284c57faa15cd896c4d5cfb2d59f32dc43d # v0.8.3
         with:
-          pixi-version: v0.45.0
+          pixi-version: v0.48.2
           cache: true
           environments: ${{ matrix.environment }}
       - name:  Prepare compiler cache
@@ -44,12 +44,22 @@ jobs:
           path: ${{ steps.prep-ccache.outputs.dir }}
           key:  ${{ github.workflow }}-ccache-${{ matrix.environment }}-${{ matrix.runs-on }}-${{ steps.prep-ccache.outputs.timestamp }}
           restore-keys: ${{ github.workflow }}-ccache-${{ matrix.environment }}-${{ matrix.runs-on }}-
+      - name: Determine number of workers
+        run: |
+          if [[ "$RUNNER_OS" == "Linux" ]]; then
+            echo "NUM_WORKERS=$(nproc)" >> $GITHUB_ENV
+          elif [[ "$RUNNER_OS" == "macOS" ]]; then
+            echo "NUM_WORKERS=$(sysctl -n hw.ncpu)" >> $GITHUB_ENV
+          elif [[ "$RUNNER_OS" == "Windows" ]]; then
+            echo "NUM_WORKERS=$($Env:NUMBER_OF_PROCESSORS)" >> $env:GITHUB_ENV
+          fi
+        shell: bash
       - name: Build xsf
-        run: pixi run --environment=tests-ci build-tests-ci
+        run: pixi run --environment=tests-ci build-tests-ci $NUM_WORKERS
       - name: Run tests
-        run: pixi run --skip-deps --environment=tests-ci tests-ci
+        run: pixi run --skip-deps --environment=tests-ci tests-ci $NUM_WORKERS
       - name: Generate converage
-        run: pixi run --skip-deps --environment=tests-ci coverage
+        run: pixi run --skip-deps --environment=tests-ci coverage $NUM_WORKERS
       - name: Upload HTML coverage report
         uses: actions/upload-artifact@b4b15b8c7c6ac21ea08fcf65892d2ee8f75cf882  # v4.4.3
         with: