Use a consistent default Python version for profiling (#938)

Author: ofek

.github/actions/latest-supported-python/action.yml

@@ -0,0 +1,46 @@
+name: Latest Supported Python
+description: Fetch the highest minor version of Python with a wheel in the latest release on PyPI
+inputs:
+  github-token:
+    description: The token to use for the GitHub API
+    required: true
+outputs:
+  version:
+    description: The highest minor version of Python with a wheel
+    value: ${{ steps.python-version.outputs.version }}
+
+runs:
+  using: composite
+  steps:
+  - name: Fetch latest release on GitHub
+    id: latest-release
+    env:
+      GH_TOKEN: ${{ inputs.github-token }}
+    shell: bash
+    run: |-
+      latest_release=$(
+        gh api "repos/${{ github.repository }}/releases/latest" \
+          --jq '.tag_name'
+      )
+      echo "Latest release: $latest_release"
+      echo "tag=$latest_release" >> $GITHUB_OUTPUT
+
+  - name: Fetch latest release on PyPI
+    id: python-version
+    shell: bash
+    run: |-
+      python_version=$(
+        curl -s "https://pypi.org/pypi/msgspec/${{ steps.latest-release.outputs.tag }}/json" \
+          | jq -r '
+            [ .urls[]
+              | select(.packagetype == "bdist_wheel")
+              | .filename
+              | capture("cp(?<cp>[0-9]+)").cp
+              | tonumber
+            ]
+            | max
+            | "3.\(tostring | .[1:])"
+          '
+      )
+      echo "Python version: $python_version"
+      echo "version=$python_version" >> $GITHUB_OUTPUT

.github/workflows/ci.yml

@@ -31,12 +31,13 @@ on:
     - published
 
 jobs:
-  validate:
+  prepare:
     name: Run static analysis and prepare build
     runs-on: ubuntu-latest
 
     outputs:
       sdist-name: "${{ steps.build-sdist.outputs.file-name }}"
+      latest-supported-python: "${{ steps.latest-supported-python.outputs.version }}"
 
     steps:
     - name: Checkout code
@@ -81,10 +82,16 @@ jobs:
         path: dist/${{ steps.build-sdist.outputs.file-name }}
         if-no-files-found: error
 
+    - name: Fetch latest supported Python
+      id: latest-supported-python
+      uses: ./.github/actions/latest-supported-python
+      with:
+        github-token: "${{ github.token }}"
+
   test:
     name: Test Python ${{ matrix.python-version }} on ${{ startsWith(matrix.os, 'macos-') && 'macOS' || startsWith(matrix.os, 'windows-') && 'Windows' || 'Linux' }}
     needs:
-    - validate
+    - prepare
     runs-on: "${{ matrix.os }}"
     strategy:
       fail-fast: false
@@ -214,7 +221,7 @@ jobs:
     name: Build wheels on ${{ matrix.os }} for ${{ matrix.archs }}
     needs:
     - test
-    - validate
+    - prepare
     runs-on: "${{ matrix.os }}"
     strategy:
       fail-fast: false
@@ -256,7 +263,7 @@ jobs:
       uses: pypa/cibuildwheel@v3.2.1
       with:
         config-file: .cibuildwheel.toml
-        package-dir: dist/${{ needs.validate.outputs.sdist-name }}
+        package-dir: dist/${{ needs.prepare.outputs.sdist-name }}
       env:
         CIBW_ARCHS: "${{ matrix.archs }}"
 
@@ -268,18 +275,20 @@ jobs:
         if-no-files-found: error
 
   profile:
-    name: Run profiling tests
+    name: Run profiling tests on Python ${{ needs.prepare.outputs.latest-supported-python }}
     needs:
+    - prepare
     - build-wheels
     uses: ./.github/workflows/profile.yml
     with:
       version: dev
+      python: "${{ needs.prepare.outputs.latest-supported-python }}"
 
   upload-pypi:
     name: Upload artifacts to PyPI
     if: github.event_name == 'release' && github.event.action == 'published'
     needs:
-    - validate
+    - prepare
     - build-wheels
     runs-on: ubuntu-latest
     permissions:

.github/workflows/profile.yml

@@ -10,7 +10,6 @@ on:
       python:
         description: Minor version of Python to use for profiling
         type: string
-        default: latest
   workflow_call:
     inputs:
       version:
@@ -20,7 +19,6 @@ on:
       python:
         description: Minor version of Python to use for profiling
         type: string
-        default: latest
 
 jobs:
   profile:
@@ -61,14 +59,21 @@ jobs:
     - name: Install command runner
       run: uv tool install rust-just
 
+    - name: Fetch latest supported Python
+      if: inputs.python == ''
+      id: latest-supported-python
+      uses: ./.github/actions/latest-supported-python
+      with:
+        github-token: "${{ github.token }}"
+
     - name: Set profiling environment metadata
       id: metadata
       shell: bash
       run: |-
+        python_version="${{ inputs.python || steps.latest-supported-python.outputs.version }}"
+        echo "UV_PYTHON=$python_version" >> $GITHUB_ENV
+        echo "python-version=$python_version" >> $GITHUB_OUTPUT
         echo "env-path=$(just env-path prof)" >> $GITHUB_OUTPUT
-        if [[ "${{ inputs.python }}" != "latest" ]]; then
-          echo "UV_PYTHON=${{ inputs.python }}" >> $GITHUB_ENV
-        fi
 
     - name: Install profiling dependencies
       env:
@@ -91,5 +96,5 @@ jobs:
         ${{ format('msgspec{0}{1}', inputs.version != 'dev' && '==' || '', inputs.version != 'dev' && inputs.version || '') }}
 
     # TODO: set up infra to commit results after each merge and then make tests compare
-    - name: Run profiling tests
+    - name: Run profiling tests on Python ${{ steps.metadata.outputs.python-version }}
       run: just test-perf all --calibrate --rounds 10000