cuda-python-bugfix: allow passage of cuda stream objects or pointers

Pointers are dangerous because they aren't reference counted and so can be deleted before
cufinufft cleans up (#417). This patch allows the user to pass either a stream object OR a
pointer in the `gpu_stream` argument of Plan

python/cufinufft/cufinufft/_compat.py

@@ -27,6 +27,22 @@ def get_array_module(obj):
         return "generic"
 
 
+def get_stream_ptr(obj):
+    framework = get_array_module(obj)
+    if isinstance(obj, int):
+        return obj
+    if framework == 'numba':
+        return obj.handle.value
+    if framework == 'pycuda':
+        return obj.handle
+    if framework == 'torch':
+        return obj.cuda_stream
+    # Unknown / generic / cupy
+    if hasattr(obj, 'ptr'):
+        return obj.ptr
+    raise TypeError("Unknown cuda stream pointer type")
+
+
 def get_array_size(obj):
     array_module = get_array_module(obj)
 

python/cufinufft/cufinufft/_plan.py

@@ -125,20 +125,26 @@ def __init__(self, nufft_type, n_modes, n_trans=1, eps=1e-6, isign=None,
         # Extract list of valid field names.
         field_names = [name for name, _ in self._opts._fields_]
 
+        # Initialize a list for references to objects
+        # we want to keep around for life of instance.
+        self._references = []
+
         # Assign field names from kwargs if they match up, otherwise error.
         for k, v in kwargs.items():
             if k in field_names:
-                setattr(self._opts, k, v)
+                if k == 'gpu_stream':
+                    # need reference to stream object to prevent stream cleanup before plan object
+                    self._references.append(v)
+                    stream_ptr = _compat.get_stream_ptr(v)
+                    setattr(self._opts, k, stream_ptr)
+                else:
+                    setattr(self._opts, k, v)
             else:
                 raise TypeError(f"Invalid option '{k}'")
 
         # Initialize the plan.
         self._init_plan()
 
-        # Initialize a list for references to objects
-        #   we want to keep around for life of instance.
-        self._references = []
-
     @staticmethod
     def _default_opts():
         """

python/cufinufft/examples/example3d2many_async_cupy.py

@@ -44,7 +44,7 @@ def test():
 
     # Initialize the plan and set the points.
     plan_stream = cupy.cuda.Stream(null=True)
-    plan = cufinufft.Plan(2, N, n_transf, eps=eps, dtype=complex_dtype, gpu_kerevalmeth=1, gpu_stream=plan_stream.ptr)
+    plan = cufinufft.Plan(2, N, n_transf, eps=eps, dtype=complex_dtype, gpu_kerevalmeth=1, gpu_stream=plan_stream)
     plan.setpts(cupy.array(x), cupy.array(y), cupy.array(z))
 
     # Using a simple front/back buffer approach. backbuffer is for DtoH transfers, and front for
@@ -54,9 +54,9 @@ def test():
     back_fk_gpu = cupy.empty(fk_all[0].shape, fk_all[0].dtype)
     front_c_gpu = cupy.empty(c_all_async[0].shape, c_all_async[0].dtype)
     back_c_gpu = cupy.empty(c_all_async[0].shape, c_all_async[0].dtype)
-    front_plan = cufinufft.Plan(2, N, n_transf, eps=eps, dtype=complex_dtype, gpu_kerevalmeth=1, gpu_stream=front_stream.ptr)
+    front_plan = cufinufft.Plan(2, N, n_transf, eps=eps, dtype=complex_dtype, gpu_kerevalmeth=1, gpu_stream=front_stream)
     front_plan.setpts(cupy.array(x), cupy.array(y), cupy.array(z))
-    back_plan = cufinufft.Plan(2, N, n_transf, eps=eps, dtype=complex_dtype, gpu_kerevalmeth=1, gpu_stream=back_stream.ptr)
+    back_plan = cufinufft.Plan(2, N, n_transf, eps=eps, dtype=complex_dtype, gpu_kerevalmeth=1, gpu_stream=back_stream)
     back_plan.setpts(cupy.array(x), cupy.array(y), cupy.array(z))
 
     # Run with async
@@ -101,10 +101,4 @@ def test():
     print(f"speedup (naive / sync): {round(naive_time / sync_time, 2)}")
     print(f"speedup (naive / async): {round(naive_time / async_time, 2)}")
 
-    # Since plans carry raw stream pointers which aren't reference counted, we need to make
-    # sure they're deleted before the stream objects that hold them. Otherwise, the stream
-    # might be deleted before cufinufft can use it in the deletion routines. Manually clear
-    # them out here.
-    del plan, front_plan, back_plan
-
 test()