BUG: Handle CUDA_PYTHON_CUDA_PER_THREAD_DEFAULT_STREAM correctly

Author: mdboom

cuda_bindings/cuda/bindings/_bindings/cydriver.pyx.in

@@ -519,7 +519,7 @@ cdef int _cuPythonInit() except -1 nogil:
     cdef char libPath[260]
 
     with gil, __symbol_lock:
-        usePTDS = os.getenv('CUDA_PYTHON_CUDA_PER_THREAD_DEFAULT_STREAM', default=0)
+        usePTDS = bool(int(os.getenv('CUDA_PYTHON_CUDA_PER_THREAD_DEFAULT_STREAM', default=0)))
 
         # Load library
         libPath[0] = 0

cuda_bindings/cuda/bindings/_bindings/cyruntime.pyx.in

@@ -15,7 +15,7 @@ cdef int _cudaPythonInit() except -1 nogil:
         global __usePTDS
 
         with gil:
-            __usePTDS = os.getenv('CUDA_PYTHON_CUDA_PER_THREAD_DEFAULT_STREAM', default=False)
+            __usePTDS = bool(int(os.getenv('CUDA_PYTHON_CUDA_PER_THREAD_DEFAULT_STREAM', default=0)))
         __cudaPythonInit = True
         return __usePTDS
 

cuda_bindings/docs/source/release/13.2.1-notes.rst

@@ -0,0 +1,14 @@
+.. SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+.. SPDX-License-Identifier: LicenseRef-NVIDIA-SOFTWARE-LICENSE
+
+.. module:: cuda.bindings
+
+``cuda-bindings`` 13.2.1 Release notes
+======================================
+
+Bugfixes
+--------
+
+* Per-thread default stream mode would be used whenever the
+  ``CUDA_PYTHON_CUDA_PER_THREAD_DEFAULT_STREAM`` environment variable was set,
+  even if it was set to ``0``.