pydantic · davidhewitt · Jul 10, 2026 · Jul 10, 2026 · Jul 10, 2026
diff --git a/.github/actions/build-pgo-wheel/action.yml b/.github/actions/build-pgo-wheel/action.yml
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -474,7 +474,7 @@ jobs:
           name: pypi_files-sdist
           path: crates/monty-python/dist
 
-  # Build wheels for exotic architectures (non-PGO)
+  # Build extension wheels and one runtime wheel for every supported platform
   build:
     name: build on ${{ matrix.os }} (${{ matrix.target }} - ${{ matrix.manylinux || 'auto' }})
     # only run on push to main, on tags, or if 'Full Build' label is present
@@ -483,35 +483,44 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          # Linux aarch64
+          - os: linux
+            target: x86_64
+            pgo-runtime: true
           - os: linux
             target: aarch64
-          # Linux i686
+            pgo-runtime: false
           - os: linux
             target: i686
-          # Linux armv7
+            pgo-runtime: false
           - os: linux
             target: armv7
-          # Linux ppc64le
+            pgo-runtime: false
           - os: linux
             target: ppc64le
-          # Linux s390x
+            pgo-runtime: false
           - os: linux
             target: s390x
-          # Linux x86_64 musl
+            pgo-runtime: false
           - os: linux
             target: x86_64
             manylinux: musllinux_1_1
-          # Linux aarch64 musl
+            pgo-runtime: false
           - os: linux
             target: aarch64
             manylinux: musllinux_1_1
-          # macOS x86_64 (Intel)
+            pgo-runtime: false
+          - os: macos
+            target: aarch64
+            pgo-runtime: true
           - os: macos
             target: x86_64
-          # Windows i686
+            pgo-runtime: false
+          - os: windows
+            target: x86_64
+            pgo-runtime: true
           - os: windows
             target: i686
+            pgo-runtime: false
 
     runs-on: ${{ (matrix.os == 'linux' && 'ubuntu-latest') || (matrix.os == 'macos' && 'macos-latest') || (matrix.os == 'windows' && 'windows-latest') }}
     steps:
@@ -523,7 +532,7 @@ jobs:
         with:
           python-version: '3.12'
 
-      - name: build wheels
+      - name: build Python wheels
         uses: PyO3/maturin-action@04ac600d27cdf7a9a280dadf7147097c42b757ad # v1.50.1
         with:
           target: ${{ matrix.target }}
@@ -533,101 +542,30 @@ jobs:
           docker-options: -e CI
           working-directory: crates/monty-python
 
-      # the pydantic-monty-runtime wheel ships the `monty` worker binary
-      # (bin bindings, one py3-none wheel per platform). `-i` is required so
-      # maturin can find a Python to read pyproject.toml — the produced wheel
-      # is `py3-none-<plat>` and doesn't depend on a specific Python version.
-      - name: build cli wheel
-        uses: PyO3/maturin-action@04ac600d27cdf7a9a280dadf7147097c42b757ad # v1.50.1
-        with:
-          target: ${{ matrix.target }}
-          manylinux: ${{ matrix.manylinux || 'manylinux_2_28' }}
-          args: --release --out dist -i 3.10 3.11 3.12 3.13 3.14
-          rust-toolchain: stable
-          docker-options: -e CI
-          working-directory: crates/monty-runtime
-
       - uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
-          name: pypi_files-${{ matrix.os }}-${{ matrix.target }}-${{ matrix.manylinux || 'manylinux' }}
+          name: pypi_files-python-${{ matrix.os }}-${{ matrix.target }}-${{ matrix.manylinux || 'manylinux' }}
           path: crates/monty-python/dist
 
-      - uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
-        with:
-          name: pypi_files-${{ matrix.os }}-${{ matrix.target }}-${{ matrix.manylinux || 'manylinux' }}-cli
-          path: crates/monty-runtime/dist
-
-  # PGO-optimized builds for main platforms
-  build-pgo:
-    name: build pgo on ${{ matrix.os }}
-    # only run on push to main, on tags, or if 'Full Build' label is present
-    if: startsWith(github.ref, 'refs/tags/') || github.ref == 'refs/heads/main' || contains(github.event.pull_request.labels.*.name, 'Full Build') || (github.event_name == 'workflow_dispatch' && inputs.run_release)
-    strategy:
-      fail-fast: false
-      matrix:
-        include:
-          # Linux x86_64 (manylinux)
-          - os: linux
-            runs-on: ubuntu-latest
-            interpreter: 3.10 3.11 3.12 3.13 3.14
-          # Windows x86_64
-          - os: windows
-            runs-on: windows-latest
-            interpreter: 3.10 3.11 3.12 3.13 3.14
-          # macOS aarch64 (Apple Silicon)
-          - os: macos
-            runs-on: macos-latest
-            interpreter: 3.10 3.11 3.12 3.13 3.14
-
-    runs-on: ${{ matrix.runs-on }}
-
-    steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-        with:
-          persist-credentials: false
-
-      - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
-        with:
-          python-version: '3.12'
-
-      # no release versioning, see https://github.com/dtolnay/rust-toolchain/issues/180
-      - uses: dtolnay/rust-toolchain@efa25f7f19611383d5b0ccf2d1c8914531636bf9
-        with:
-          toolchain: stable
-          components: llvm-tools
-
-      - name: build PGO wheel
-        id: pgo
-        uses: ./.github/actions/build-pgo-wheel
-        with:
-          interpreter: ${{ matrix.interpreter }}
-          rust-toolchain: stable
-
-      # the PGO-optimized cli wheel for the main platforms — reuses the
-      # merged profile data from the build-pgo-wheel action above (which
-      # exercised an instrumented monty binary via `exercise.py`).
-      # `-i` is required so maturin can find a Python to read pyproject.toml
-      # inside the manylinux docker container; the produced wheel is
-      # `py3-none-<plat>` and doesn't depend on a specific Python version.
-      - name: build cli wheel
+      # Maturin performs one PGO cycle for bin bindings, then packages the
+      # runtime for each supported Python tag.
+      - name: build runtime wheel
         uses: PyO3/maturin-action@04ac600d27cdf7a9a280dadf7147097c42b757ad # v1.50.1
         with:
-          manylinux: manylinux_2_28
-          args: --release --out dist -i 3.10 3.11 3.12 3.13 3.14
+          target: ${{ matrix.target }}
+          manylinux: ${{ matrix.manylinux || 'manylinux_2_28' }}
+          # FIXME: should not need `-i`
+          # see https://github.com/PyO3/maturin/issues/3256 which causes per-version builds
+          args: --release ${{ matrix.pgo-runtime && '--pgo' || '' }} --out dist -i 3.10 3.11 3.12 3.13 3.14
+          maturin-version: v1.14.1
           rust-toolchain: stable
+          rustup-components: ${{ matrix.pgo-runtime && 'llvm-tools-preview' || '' }}
           docker-options: -e CI
           working-directory: crates/monty-runtime
-        env:
-          RUSTFLAGS: '-Cprofile-use=${{ github.workspace }}/merged.profdata'
 
       - uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
-          name: pypi_files-${{ matrix.os }}-pgo
-          path: ${{ steps.pgo.outputs.wheel-dir }}
-
-      - uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
-        with:
-          name: pypi_files-${{ matrix.os }}-pgo-cli
+          name: pypi_files-runtime-${{ matrix.os }}-${{ matrix.target }}-${{ matrix.manylinux || 'manylinux' }}
           path: crates/monty-runtime/dist
 
   # Test wheels on exotic architectures via QEMU
@@ -648,7 +586,7 @@ jobs:
 
       - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
-          pattern: pypi_files-linux-${{ matrix.target }}-*
+          pattern: pypi_files-*-linux-${{ matrix.target }}-*
           merge-multiple: true
           path: dist
 
@@ -679,7 +617,7 @@ jobs:
   # Test wheels on main OS platforms
   test-builds-os:
     name: test build on ${{ matrix.os }}
-    needs: [build, build-pgo]
+    needs: [build]
     runs-on: ${{ matrix.runs-on }}
 
     strategy:
@@ -704,7 +642,7 @@ jobs:
 
       - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
-          pattern: pypi_files-${{ matrix.os }}-*
+          pattern: pypi_files-*-${{ matrix.os }}-*
           merge-multiple: true
           path: dist
 
@@ -736,7 +674,7 @@ jobs:
 
   # Inspect built artifacts
   inspect-python-assets:
-    needs: [build, build-pgo, build-sdist]
+    needs: [build, build-sdist]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
@@ -745,11 +683,12 @@ jobs:
           merge-multiple: true
           path: dist
 
+      # FIXME: the count needs updating if the runtime can be built as a single version-agnostic wheel
       - name: list files
         run: |
           ls -lhR dist/
           ls -1 dist/ | wc -l
-          echo "Expected ~62 files (5 Python versions × 10 platform variants + 12 cli wheels + sdists)"
+          echo "Expected 122 files (5 Python versions × 12 platform variants × 2 packages + 2 sdists)"
 
       - uses: astral-sh/setup-uv@cec208311dfd045dd5311c1add060b2062131d57 # v8.0.0
         with:

diff --git a/CLAUDE.md b/CLAUDE.md
@@ -274,7 +274,7 @@ make build-wasm           Build the lean wasm worker module (requires the wasm32
 make test-wasm            Test the wasm worker pool/transport (requires a prior build-wasm)
 make build-cpython-image  Build the monty-cpython docker image (locally by default)
 make upload-cpython-image Build the monty-cpython docker image and push to ghcr.io/pydantic/monty-cpython
-make dev-py-pgo           Install the python package for development with profile-guided optimization
+make dev-py-pgo           Install the Python package with a PGO-optimized Monty runtime
 make format-rs            Format Rust code with fmt
 make format-py            Format Python code - WARNING be careful about this command as it may modify code and break tests silently!
 make format-js            Format JS code with prettier

diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Makefile b/Makefile
@@ -92,14 +92,12 @@ upload-cpython-image: ## Build the monty-cpython docker image and push to ghcr.i
 		BUILDX_OUTPUT=--push
 
 .PHONY: dev-py-pgo
-dev-py-pgo: ## Install the python package for development with profile-guided optimization
-	$(eval PROFDATA := $(shell mktemp -d))
-	RUSTFLAGS='-Cprofile-generate=$(PROFDATA)' uv run maturin develop --uv -m crates/monty-python/Cargo.toml --release
-	uv run --package pydantic-monty --only-dev pytest crates/monty-python/tests -k "not test_parallel_exec"
-	$(eval LLVM_PROFDATA := $(shell rustup run stable bash -c 'echo $$RUSTUP_HOME/toolchains/$$RUSTUP_TOOLCHAIN/lib/rustlib/$$(rustc -Vv | grep host | cut -d " " -f 2)/bin/llvm-profdata'))
-	$(LLVM_PROFDATA) merge -o $(PROFDATA)/merged.profdata $(PROFDATA)
-	RUSTFLAGS='-Cprofile-use=$(PROFDATA)/merged.profdata' $(uv-run-no-sync) maturin develop --uv -m crates/monty-python/Cargo.toml --release
-	@rm -rf $(PROFDATA)
+dev-py-pgo: ## Install the Python package with a PGO-optimized Monty interpreter
+	rustup component add llvm-tools --toolchain stable
+	rm -rf target/pgo-wheels
+	uvx --from 'maturin==1.14.1' maturin build -m crates/monty-runtime/Cargo.toml --release --pgo -i "$$(uv run python -c 'import sys; print(sys.executable)')" --out target/pgo-wheels
+	uv pip install --python "$$(uv run python -c 'import sys; print(sys.executable)')" --reinstall --no-deps target/pgo-wheels/pydantic_monty_runtime-*.whl
+	uv run maturin develop --uv -m crates/monty-python/Cargo.toml --release
 
 .PHONY: format-rs
 format-rs:  ## Format Rust code with fmt

diff --git a/crates/monty-datatest/Cargo.toml b/crates/monty-datatest/Cargo.toml
@@ -7,9 +7,11 @@ edition = { workspace = true }
 authors = { workspace = true }
 description = "Datatest harness for Monty — runs test cases against both Monty and CPython"
 publish = false
+default-run = "monty-datatest"
 
 [dependencies]
 monty = { workspace = true, features = ["test-hooks"] }
+monty-pool = { workspace = true }
 pyo3 = { workspace = true, features = ["auto-initialize"] }
 ahash = { workspace = true }
 chrono = "0.4"