Test using pytest-run-parallel and related fixups in the tests

ci/tools/run-tests

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 #
 # SPDX-License-Identifier: Apache-2.0
 
@@ -20,6 +20,14 @@ fi
 
 test_module=${1}
 
+FREE_THREADING=""
+PYTEST_PARALLEL_ARGS=()
+if python -c 'import sys; assert not sys._is_gil_enabled()' 2> /dev/null; then
+  FREE_THREADING="-ft"
+  PYTEST_PARALLEL_ARGS=(--parallel-threads=4)
+  pip install pytest-run-parallel
+fi
+
 # For standard modes, install pathfinder up front (it is a direct dependency
 # of bindings, and a transitive dependency of core).  Nightly modes install
 # all wheels together in a single pip call further below.
@@ -36,7 +44,7 @@ if [[ "${test_module}" == "pathfinder" ]]; then
     "LD:${CUDA_PATHFINDER_TEST_LOAD_NVIDIA_DYNAMIC_LIB_STRICTNESS} " \
     "FH:${CUDA_PATHFINDER_TEST_FIND_NVIDIA_HEADERS_STRICTNESS} " \
     "BC:${CUDA_PATHFINDER_TEST_FIND_NVIDIA_BITCODE_LIB_STRICTNESS}"
-  pytest -ra -s -v --durations=0 tests/ |& tee /tmp/pathfinder_test_log.txt
+  pytest -ra -s -v --durations=0 "${PYTEST_PARALLEL_ARGS[@]}" tests/ |& tee /tmp/pathfinder_test_log.txt
   # Report the number of "INFO test_" lines (including zero)
   # to support quick validations based on GHA log archives.
   line_count=$(awk '/^INFO test_/ {count++} END {print count+0}' /tmp/pathfinder_test_log.txt)
@@ -51,21 +59,16 @@ elif [[ "${test_module}" == "bindings" ]]; then
     pip install $(ls "${CUDA_BINDINGS_ARTIFACTS_DIR}"/*.whl)[all] --group test
   fi
   echo "Running bindings tests"
-  ${SANITIZER_CMD} pytest -rxXs -v --durations=0 --randomly-dont-reorganize tests/
+  ${SANITIZER_CMD} pytest -rxXs -v --durations=0 --randomly-dont-reorganize "${PYTEST_PARALLEL_ARGS[@]}" tests/
   if [[ "${SKIP_CYTHON_TEST}" == 0 ]]; then
-    ${SANITIZER_CMD} pytest -rxXs -v --durations=0 --randomly-dont-reorganize tests/cython
+    ${SANITIZER_CMD} pytest -rxXs -v --durations=0 --randomly-dont-reorganize "${PYTEST_PARALLEL_ARGS[@]}" tests/cython
   fi
   popd
 elif [[ "${test_module}" == "core" || "${test_module}" == nightly-* ]]; then
   # Shared setup for core and nightly modes.
   TEST_CUDA_MAJOR="$(cut -d '.' -f 1 <<< ${CUDA_VER})"
   TEST_CUDA_MAJOR_MINOR="$(cut -d '.' -f 1-2 <<< "${CUDA_VER}")"
 
-  FREE_THREADING=""
-  if python -c 'import sys; assert not sys._is_gil_enabled()' 2> /dev/null; then
-    FREE_THREADING+="-ft"
-  fi
-
   # Resolve bindings based on BINDINGS_SOURCE (set by env-vars):
   #   main/backport → local wheel from artifacts dir
   #   published     → install from PyPI by version
@@ -105,11 +108,11 @@ elif [[ "${test_module}" == "core" || "${test_module}" == nightly-* ]]; then
     echo "Installed packages before core tests:"
     pip list
     echo "Running core tests"
-    ${SANITIZER_CMD} pytest -rxXs -v --durations=0 --randomly-dont-reorganize tests/
+    ${SANITIZER_CMD} pytest -rxXs -v --durations=0 --randomly-dont-reorganize "${PYTEST_PARALLEL_ARGS[@]}" tests/
     # Currently our CI always installs the latest bindings (from either major version).
     # This is not compatible with the test requirements.
     if [[ "${SKIP_CYTHON_TEST}" == 0 ]]; then
-      ${SANITIZER_CMD} pytest -rxXs -v --durations=0 --randomly-dont-reorganize tests/cython
+      ${SANITIZER_CMD} pytest -rxXs -v --durations=0 --randomly-dont-reorganize "${PYTEST_PARALLEL_ARGS[@]}" tests/cython
     fi
     popd
   elif [[ "${test_module}" == "nightly-cuda-core" ]]; then

cuda_bindings/tests/test_cufile.py

@@ -138,7 +138,7 @@ def ctx():
     (err,) = cuda.cuCtxSetCurrent(ctx)
     assert err == cuda.CUresult.CUDA_SUCCESS
 
-    yield
+    yield ctx
 
     cuda.cuDevicePrimaryCtxRelease(device)
 

cuda_bindings/tests/test_examples.py

@@ -20,6 +20,7 @@ def test_example(example):
 
     env = os.environ.copy()
     env["CUDA_BINDINGS_SKIP_EXAMPLE"] = "100"
+    env["MPLBACKEND"] = "Agg"  # avoid plt.show() from blocking
 
     process = subprocess.run([sys.executable, example], capture_output=True, env=env)  # noqa: S603
     # returncode is a special value used in the examples to indicate that system requirements are not met.

cuda_core/cuda/core/_memory/_buffer.pyx

@@ -272,8 +272,11 @@ cdef class Buffer:
     @cython.critical_section
     def ipc_descriptor(self) -> IPCBufferDescriptor:
         """Descriptor for sharing this buffer with other processes."""
+        cdef object ipc_data
         if self._ipc_data is None:
-            self._ipc_data = IPCDataForBuffer(_ipc.Buffer_get_ipc_descriptor(self), False)
+            ipc_data = IPCDataForBuffer(_ipc.Buffer_get_ipc_descriptor(self), False)
+            if self._ipc_data is None:
+                self._ipc_data = ipc_data
         return self._ipc_data.ipc_descriptor
 
     def close(self, stream: Stream | GraphBuilder | None = None) -> None:

cuda_core/cuda/core/_memory/_memory_pool.pyx

@@ -183,8 +183,11 @@ cdef class _MemPool(MemoryResource):
     @cython.critical_section
     def attributes(self) -> _MemPoolAttributes:
         """Memory pool attributes."""
+        cdef _MemPoolAttributes attributes
         if self._attributes is None:
-            self._attributes = _MemPoolAttributes._init(self._h_pool)
+            attributes = _MemPoolAttributes._init(self._h_pool)
+            if self._attributes is None:
+                self._attributes = attributes
         return self._attributes
 
     @property

cuda_core/cuda/core/_memoryview.pyx

@@ -544,13 +544,16 @@ cdef class StridedMemoryView:
 
     @cython.critical_section
     cdef inline _StridedLayout get_layout(self):
+        cdef _StridedLayout layout
         if self._layout is None:
             if self.dl_tensor:
-                self._layout = layout_from_dlpack(self.dl_tensor)
+                layout = layout_from_dlpack(self.dl_tensor)
             elif self.metadata is not None:
-                self._layout = layout_from_cai(self.metadata)
+                layout = layout_from_cai(self.metadata)
             else:
                 raise ValueError("Cannot infer layout from the exporting object")
+            if self._layout is None:
+                self._layout = layout
         return self._layout
 
     @cython.critical_section
@@ -560,24 +563,31 @@ cdef class StridedMemoryView:
         If the SMV was created from a Buffer, it will return the same Buffer instance.
         Otherwise, it will create a new instance with owner set to the exporting object.
         """
+        cdef object buffer
         if self._buffer is None:
             if isinstance(self.exporting_obj, Buffer):
-                self._buffer = self.exporting_obj
+                buffer = self.exporting_obj
             else:
-                self._buffer = Buffer.from_handle(self.ptr, 0, owner=self.exporting_obj)
+                buffer = Buffer.from_handle(self.ptr, 0, owner=self.exporting_obj)
+            if self._buffer is None:
+                self._buffer = buffer
         return self._buffer
 
     @cython.critical_section
     cdef inline object get_dtype(self):
+        cdef object dtype
         if self._dtype is None:
+            dtype = None
             if self.dl_tensor != NULL:
-                self._dtype = dtype_dlpack_to_numpy(&self.dl_tensor.dtype)
+                dtype = dtype_dlpack_to_numpy(&self.dl_tensor.dtype)
             elif isinstance(self.metadata, int):
                 # AOTI dtype code stored by the torch tensor bridge
-                self._dtype = _get_tensor_bridge().resolve_aoti_dtype(
+                dtype = _get_tensor_bridge().resolve_aoti_dtype(
                     self.metadata)
             elif self.metadata is not None:
-                self._dtype = _typestr2dtype(self.metadata["typestr"])
+                dtype = _typestr2dtype(self.metadata["typestr"])
+            if self._dtype is None:
+                self._dtype = dtype
         return self._dtype
 
 

cuda_core/cuda/core/_module.pyx

@@ -459,8 +459,11 @@ cdef class Kernel:
     @cython.critical_section
     def attributes(self) -> KernelAttributes:
         """Get the read-only attributes of this kernel."""
+        cdef KernelAttributes attributes
         if self._attributes is None:
-            self._attributes = KernelAttributes._init(self._h_kernel)
+            attributes = KernelAttributes._init(self._h_kernel)
+            if self._attributes is None:
+                self._attributes = attributes
         return self._attributes
 
     cdef tuple _get_arguments_info(self, bint param_info=False):
@@ -507,8 +510,11 @@ cdef class Kernel:
     @cython.critical_section
     def occupancy(self) -> KernelOccupancy:
         """Get the occupancy information for launching this kernel."""
+        cdef KernelOccupancy occupancy
         if self._occupancy is None:
-            self._occupancy = KernelOccupancy._init(self._h_kernel)
+            occupancy = KernelOccupancy._init(self._h_kernel)
+            if self._occupancy is None:
+                self._occupancy = occupancy
         return self._occupancy
 
     @property
@@ -748,24 +754,28 @@ cdef class ObjectCode:
 
     @cython.critical_section
     cdef int _lazy_load_module(self) except -1:
+        cdef LibraryHandle _h_library
         if self._h_library:
             return 0
         module = self._module
         cdef bytes path_bytes
         if isinstance(module, str):
             path_bytes = module.encode()
-            self._h_library = create_library_handle_from_file(<const char*>path_bytes)
+            _h_library = create_library_handle_from_file(<const char*>path_bytes)
         elif isinstance(module, (bytes, bytearray)):
-            self._h_library = create_library_handle_from_data(<const void*><char*>module)
+            _h_library = create_library_handle_from_data(<const void*><char*>module)
         elif isinstance(module, PathLike):
             path_bytes = fsencode(module)
-            self._h_library = create_library_handle_from_file(<const char*>path_bytes)
+            _h_library = create_library_handle_from_file(<const char*>path_bytes)
         else:
             assert_type_str_or_bytes_like(module)
             raise_code_path_meant_to_be_unreachable()
             return -1
-        if not self._h_library:
+        if not _h_library:
             HANDLE_RETURN(get_last_error())
+
+        if not self._h_library:
+            self._h_library = _h_library
         return 0
 
     def get_kernel(self, name: str | bytes) -> Kernel: