Backport #986 & #1005

.github/workflows/build-wheel.yml

@@ -30,6 +30,9 @@ jobs:
           - "3.11"
           - "3.12"
           - "3.13"
+          - "3.13t"
+          - "3.14"
+          - "3.14t"
     name: py${{ matrix.python-version }}
     runs-on: ${{ (inputs.host-platform == 'linux-64' && 'linux-amd64-cpu8') ||
                  (inputs.host-platform == 'linux-aarch64' && 'linux-arm64-cpu8') ||
@@ -116,6 +119,7 @@ jobs:
           CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: "delvewheel repair --namespace-pkg cuda -w {dest_dir} {wheel}"
           CIBW_ENVIRONMENT: >
             CUDA_PYTHON_PARALLEL_LEVEL=${{ env.CUDA_PYTHON_PARALLEL_LEVEL }}
+          CIBW_ENABLE: "cpython-freethreading"
         with:
           package-dir: ./cuda_core/
           output-dir: ${{ env.CUDA_CORE_ARTIFACTS_DIR }}
@@ -163,6 +167,7 @@ jobs:
             CUDA_PYTHON_PARALLEL_LEVEL=${{ env.CUDA_PYTHON_PARALLEL_LEVEL }}
           CIBW_BEFORE_BUILD_WINDOWS: "pip install delvewheel"
           CIBW_REPAIR_WHEEL_COMMAND_WINDOWS: "delvewheel repair --namespace-pkg cuda -w {dest_dir} {wheel}"
+          CIBW_ENABLE: "cpython-freethreading"
         with:
           package-dir: ./cuda_bindings/
           output-dir: ${{ env.CUDA_BINDINGS_ARTIFACTS_DIR }}
@@ -222,6 +227,12 @@ jobs:
         with:
           # workaround for actions/runner-images#12377 (the cached 3.13.4 is buggy on Windows)
           python-version: ${{ matrix.python-version == '3.13' && '3.13.5' || matrix.python-version }}
+          # allow prereleases only fetches prereleases for unreleased versions of Python
+          allow-prereleases: true
+
+      - name: verify free-threaded build
+        if: endsWith(matrix.python-verison, 't')
+        run: python -c 'import sys; assert not sys._is_gil_enabled()'
 
       - name: Set up Python include paths
         run: |

.github/workflows/test-wheel-linux.yml

@@ -215,6 +215,7 @@ jobs:
         uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065  # v5.6.0
         with:
           python-version: ${{ matrix.PY_VER }}
+          allow-prereleases: true
         env:
           # we use self-hosted runners on which setup-python behaves weirdly...
           AGENT_TOOLSDIRECTORY: "/opt/hostedtoolcache"

.github/workflows/test-wheel-windows.yml

@@ -203,6 +203,7 @@ jobs:
         uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065  # v5.6.0
         with:
           python-version: ${{ matrix.PY_VER }}
+          allow-prereleases: true
 
       - name: Set up mini CTK
         if: ${{ matrix.LOCAL_CTK == '1' }}

ci/test-matrix.json

@@ -14,7 +14,9 @@
       { "ARCH": "amd64", "PY_VER": "3.12", "CUDA_VER": "13.0.1", "LOCAL_CTK": "0", "GPU": "l4", "DRIVER": "latest" },
       { "ARCH": "amd64", "PY_VER": "3.13", "CUDA_VER": "12.9.1", "LOCAL_CTK": "0", "GPU": "l4", "DRIVER": "latest" },
       { "ARCH": "amd64", "PY_VER": "3.13", "CUDA_VER": "13.0.1", "LOCAL_CTK": "1", "GPU": "l4", "DRIVER": "latest" },
-      { "ARCH": "amd64", "PY_VER": "3.13t", "CUDA_VER": "13.0.1", "LOCAL_CTK": "1", "GPU": "l4", "DRIVER": "latest" },
+      { "ARCH": "amd64", "PY_VER": "3.13t", "CUDA_VER": "12.9.1", "LOCAL_CTK": "1", "GPU": "l4", "DRIVER": "latest" },
+      { "ARCH": "amd64", "PY_VER": "3.14", "CUDA_VER": "12.9.1", "LOCAL_CTK": "1", "GPU": "l4", "DRIVER": "latest" },
+      { "ARCH": "amd64", "PY_VER": "3.14t", "CUDA_VER": "12.9.1", "LOCAL_CTK": "0", "GPU": "l4", "DRIVER": "latest" },
       { "ARCH": "arm64", "PY_VER": "3.9",  "CUDA_VER": "12.9.1", "LOCAL_CTK": "0", "GPU": "a100", "DRIVER": "latest" },
       { "ARCH": "arm64", "PY_VER": "3.9",  "CUDA_VER": "13.0.1", "LOCAL_CTK": "1", "GPU": "a100", "DRIVER": "latest" },
       { "ARCH": "arm64", "PY_VER": "3.10", "CUDA_VER": "12.9.1", "LOCAL_CTK": "1", "GPU": "a100", "DRIVER": "latest" },
@@ -25,7 +27,9 @@
       { "ARCH": "arm64", "PY_VER": "3.12", "CUDA_VER": "13.0.1", "LOCAL_CTK": "0", "GPU": "a100", "DRIVER": "latest" },
       { "ARCH": "arm64", "PY_VER": "3.13", "CUDA_VER": "12.9.1", "LOCAL_CTK": "0", "GPU": "a100", "DRIVER": "latest" },
       { "ARCH": "arm64", "PY_VER": "3.13", "CUDA_VER": "13.0.1", "LOCAL_CTK": "1", "GPU": "a100", "DRIVER": "latest" },
-      { "ARCH": "arm64", "PY_VER": "3.13t", "CUDA_VER": "13.0.1", "LOCAL_CTK": "1", "GPU": "a100", "DRIVER": "latest" }
+      { "ARCH": "arm64", "PY_VER": "3.13t", "CUDA_VER": "12.9.1", "LOCAL_CTK": "1", "GPU": "a100", "DRIVER": "latest" },
+      { "ARCH": "arm64", "PY_VER": "3.14", "CUDA_VER": "12.9.1", "LOCAL_CTK": "1", "GPU": "a100", "DRIVER": "latest" },
+      { "ARCH": "arm64", "PY_VER": "3.14t", "CUDA_VER": "12.9.1", "LOCAL_CTK": "0", "GPU": "a100", "DRIVER": "latest" }
     ],
     "nightly": [
       { "ARCH": "amd64", "PY_VER": "3.9",  "CUDA_VER": "11.8.0", "LOCAL_CTK": "0", "GPU": "l4", "DRIVER": "earliest" },

ci/tools/run-tests

@@ -75,12 +75,18 @@ elif [[ "${test_module}" == "core" ]]; then
   echo "Installing core wheel"
   pwd
   ls
+
+  FREE_THREADING=""
+  if python -c 'import sys; assert not sys._is_gil_enabled()' 2> /dev/null; then
+    FREE_THREADING+="-ft"
+  fi
+
   if [[ "${LOCAL_CTK}" == 1 ]]; then
     # We already installed cuda-bindings, and all CTK components exist locally,
     # so just install the test dependencies.
-    pip install $(ls *.whl)["test-cu${TEST_CUDA_MAJOR}"]
+    pip install $(ls *.whl)["test-cu${TEST_CUDA_MAJOR}${FREE_THREADING}"]
   else
-    pip install $(ls *.whl)["cu${TEST_CUDA_MAJOR}","test-cu${TEST_CUDA_MAJOR}"]
+    pip install $(ls *.whl)["cu${TEST_CUDA_MAJOR}","test-cu${TEST_CUDA_MAJOR}${FREE_THREADING}"]
   fi
   popd
   pushd ./cuda_core

cuda_bindings/pyproject.toml

@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: LicenseRef-NVIDIA-SOFTWARE-LICENSE
 
 [build-system]
-requires = ["setuptools>=77.0.0", "cython>=3.0,<3.1.0", "pyclibrary>=0.1.7"]
+requires = ["setuptools>=77.0.0", "cython>=3.1,<3.2", "pyclibrary>=0.1.7"]
 build-backend = "setuptools.build_meta"
 
 [project]
@@ -39,7 +39,7 @@ all = [
 ]
 
 test = [
-    "cython>=3.0,<3.1.0",
+    "cython>=3.1,<3.2",
     "setuptools>=77.0.0",
     "numpy>=1.21.1",
     "pytest>=6.2.4",