RMM 26.12 Migration Guide

Removed CUDA Stream View API

RMM 26.12 removes the deprecated rmm::cuda_stream_view class and <rmm/cuda_stream_view.hpp> header. Use cuda::stream_ref from <cuda/stream> instead. Replace calls to the view’s .value() and .synchronize() methods with .get() and .sync(), respectively.

Views of Owning Streams

rmm::cuda_stream::view() and the conversion to rmm::cuda_stream_view are removed. Use the existing implicit conversion to cuda::stream_ref:

#include <rmm/cuda_stream.hpp>

#include <cuda/stream>

rmm::cuda_stream stream;
cuda::stream_ref ref = stream;

Default Stream Constants

The deprecated stream constants are also removed:

Removed API	Replacement
rmm::cuda_stream_view{} or rmm::cuda_stream_default	cuda::stream_ref{cudaStream_t{cudaStreamDefault}}
rmm::cuda_stream_legacy	cuda::stream_ref{cudaStreamLegacy}
rmm::cuda_stream_per_thread	cuda::stream_ref{cudaStreamPerThread}

Cython Declarations

rmm.librmm.cuda_stream_view is removed. Import the replacement type from rmm.librmm.cuda_stream_ref and update declarations to use stream_ref:

from rmm.librmm.cuda_stream_ref cimport stream_ref

Explicit Streams for exec_policy and device_buffer

exec_policy and exec_policy_nosync Require a Stream

The rmm::exec_policy and rmm::exec_policy_nosync constructors no longer default to the default stream. Pass the stream explicitly:

#include <rmm/exec_policy.hpp>

#include <cuda/stream>

// Before
auto policy = rmm::exec_policy();

// After
auto policy = rmm::exec_policy(stream);

To keep the previous behavior, pass cuda::stream_ref{cudaStream_t{cudaStreamDefault}}.

Empty device_buffer Has an Invalid Stream

A default-constructed rmm::device_buffer, and a device_buffer that has been moved from, now return an invalid stream (cuda::stream_ref{cuda::invalid_stream_t{}}) from stream() instead of the default stream. Specify a stream, for example with set_stream(), before relying on stream() for an empty buffer.