Added CPython free-threading support and basic CI env

+ multithread tests
+ wheels job

.github/workflows/test.yml

@@ -96,3 +96,31 @@ jobs:
       - name: Run tests
         run: |
           pytest -n auto
+  build-free-threading:
+    # Later we can merge this job with build similarly to
+    # https://github.com/python-pillow/Pillow/blob/f0d8fd3059bc1b291563d8a0b1f224b6fd7d0b90/.github/workflows/test.yml#L56-L57
+    name: Python 3.13 with free-threading
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # ratchet:actions/checkout@v4
+        with:
+          submodules: true
+      - name: Set up Python 3.13 with free-threading
+        # TODO: replace with setup-python when there is support
+        uses: deadsnakes/action@6c8b9b82fe0b4344f4b98f2775fcc395df45e494 # v3.1.0
+        with:
+            python-version: '3.13-dev'
+            nogil: true
+      - name: Install dependencies
+        run: |
+            python -m pip install --upgrade pip
+            python -m pip install setuptools wheel
+            python -m pip install -U --pre numpy \
+              -i https://pypi.anaconda.org/scientific-python-nightly-wheels/simple
+            python -c "import numpy; print(f'{numpy.__version__=}')"
+      - name: Build ml_dtypes
+        run: |
+            python -m pip install .[dev] --no-build-isolation
+      - name: Run tests
+        run: |
+          pytest -n auto

.github/workflows/wheels.yml

@@ -40,17 +40,20 @@ jobs:
           platforms: all
 
       - name: Install cibuildwheel
-        run: python -m pip install cibuildwheel==2.15.0
+        run: python -m pip install cibuildwheel==2.20.0
 
       - name: Build wheels
         run: python -m cibuildwheel --output-dir wheelhouse
         env:
           CIBW_ARCHS_LINUX: auto aarch64
           CIBW_ARCHS_MACOS: universal2
-          CIBW_BUILD: cp39-* cp310-* cp311-* cp312-*
-          CIBW_SKIP: "*musllinux* *i686* *win32*"
+          CIBW_BUILD: cp39-* cp310-* cp311-* cp312-* cp313*
+          CIBW_FREE_THREADED_SUPPORT: True
+          CIBW_PRERELEASE_PYTHONS: True
+          CIBW_SKIP: "*musllinux* *i686* *win32* *t-win*"
           CIBW_TEST_REQUIRES: absl-py pytest pytest-xdist
           CIBW_TEST_COMMAND: pytest -n auto {project}
+          CIBW_BUILD_VERBOSITY: 1
 
       - uses: actions/upload-artifact@834a144ee995460fba8ed112a2fc961b36a5ec5a # ratchet: actions/upload-artifact@v4
         with:

ml_dtypes/_src/dtypes.cc

@@ -460,6 +460,11 @@ extern "C" EXPORT_SYMBOL PyObject* PyInit__ml_dtypes_ext() {
           reinterpret_cast<PyObject*>(TypeDescriptor<uint4>::type_ptr)) < 0) {
     return nullptr;
   }
+
+#ifdef Py_GIL_DISABLED
+  PyUnstable_Module_SetGIL(m.get(), Py_MOD_GIL_NOT_USED);
+#endif
+
   return m.release();
 }
 }  // namespace ml_dtypes

ml_dtypes/tests/conftest.py

@@ -0,0 +1,5 @@
+import sys
+from pathlib import Path
+
+# Add ml_dtypes/tests folder to discover multi_thread_utils.py module
+sys.path.insert(0, str(Path(__file__).absolute().parent))

ml_dtypes/tests/custom_float_test.py

@@ -28,6 +28,7 @@
 from absl.testing import parameterized
 import ml_dtypes
 import numpy as np
+from multi_thread_utils import multi_threaded
 
 bfloat16 = ml_dtypes.bfloat16
 float8_e3m4 = ml_dtypes.float8_e3m4
@@ -196,6 +197,10 @@ def dtype_has_inf(dtype):
 
 
 # pylint: disable=g-complex-comprehension
+@multi_threaded(
+    num_workers=3,
+    skip_tests=["testDiv", "testRoundTripNumpyTypes", "testRoundTripNumpy"],
+)
 @parameterized.named_parameters(
     (
         {"testcase_name": "_" + dtype.__name__, "float_type": dtype}
@@ -604,6 +609,19 @@ def testDtypeFromString(self, float_type):
 
 
 # pylint: disable=g-complex-comprehension
+@multi_threaded(
+    num_workers=3,
+    skip_tests=[
+        "testBinaryUfunc",
+        "testConformNumpyComplex",
+        "testFloordivCornerCases",
+        "testDivmodCornerCases",
+        "testSpacing",
+        "testUnaryUfunc",
+        "testCasts",
+        "testLdexp",
+    ],
+)
 @parameterized.named_parameters(
     (
         {"testcase_name": "_" + dtype.__name__, "float_type": dtype}

ml_dtypes/tests/finfo_test.py

@@ -16,6 +16,7 @@
 from absl.testing import parameterized
 import ml_dtypes
 import numpy as np
+from multi_thread_utils import multi_threaded
 
 ALL_DTYPES = [
     ml_dtypes.bfloat16,
@@ -41,6 +42,7 @@
 }
 
 
+@multi_threaded(num_workers=3)
 class FinfoTest(parameterized.TestCase):
 
   def assertNanEqual(self, x, y):

ml_dtypes/tests/iinfo_test.py

@@ -16,8 +16,10 @@
 from absl.testing import parameterized
 import ml_dtypes
 import numpy as np
+from multi_thread_utils import multi_threaded
 
 
+@multi_threaded(num_workers=3)
 class IinfoTest(parameterized.TestCase):
 
   def testIinfoInt2(self):

ml_dtypes/tests/intn_test.py

@@ -24,6 +24,7 @@
 from absl.testing import parameterized
 import ml_dtypes
 import numpy as np
+from multi_thread_utils import multi_threaded
 
 int2 = ml_dtypes.int2
 int4 = ml_dtypes.int4
@@ -48,6 +49,7 @@ def ignore_warning(**kw):
 
 
 # Tests for the Python scalar type
+@multi_threaded(num_workers=3)
 class ScalarTest(parameterized.TestCase):
 
   @parameterized.product(scalar_type=INTN_TYPES)
@@ -245,6 +247,7 @@ def testCanCast(self, a, b):
 
 
 # Tests for the Python scalar type
+@multi_threaded(num_workers=3, skip_tests=["testBinaryUfuncs"])
 class ArrayTest(parameterized.TestCase):
 
   @parameterized.product(scalar_type=INTN_TYPES)

ml_dtypes/tests/metadata_test.py

@@ -16,8 +16,10 @@
 
 from absl.testing import absltest
 import ml_dtypes
+from multi_thread_utils import multi_threaded
 
 
+@multi_threaded(num_workers=3)
 class CustomFloatTest(absltest.TestCase):
 
   def test_version_matches_package_metadata(self):

ml_dtypes/tests/multi_thread_utils.py

@@ -0,0 +1,29 @@
+from typing import Optional
+from concurrent.futures import ThreadPoolExecutor
+from functools import wraps
+
+
+def multi_threaded(*, num_workers: int, skip_tests: Optional[list[str]] = None):
+  def decorator(test_cls):
+    for name, test_fn in test_cls.__dict__.copy().items():
+      if not (name.startswith("test") and callable(test_fn)):
+        continue
+
+      if skip_tests is not None:
+        if any(test_name in name for test_name in skip_tests):
+          continue
+
+      @wraps(test_fn)
+      def multi_threaded_test_fn(*args, __test_fn__=test_fn, **kwargs):
+        with ThreadPoolExecutor(max_workers=num_workers) as executor:
+          futures = []
+          for _ in range(num_workers):
+            futures.append(executor.submit(__test_fn__, *args, **kwargs))
+          # We should call future.result() to re-raise an exception if test has failed
+          list(f.result() for f in futures)
+
+      setattr(test_cls, f"{name}_multi_threaded", multi_threaded_test_fn)
+
+    return test_cls
+
+  return decorator

pyproject.toml

@@ -21,6 +21,7 @@ dependencies = [
     "numpy>=1.21.2; python_version>='3.10'",
     "numpy>=1.23.3; python_version>='3.11'",
     "numpy>=1.26.0; python_version>='3.12'",
+    "numpy>=2.1.0; python_version>='3.13'",
 ]
 
 [project.urls]