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RSN 50 - Dropping of UCX-Py project in RAPIDS Release v25.10

Author RAPIDS TPM
Status

In Progress
Topic Platform Support Change
RAPIDS Version v25.10+
Created 10 July 2025
Updated N/A

Overview

RAPIDS will stop publishing UCX-Py packages in RAPIDS Release v25.10, scheduled for October 09, 2025. UCX-Py 0.45 in RAPIDS Release v25.08 will be its last. Development for the UCX-Py repository will stop, the repository will be archived and no new packages will be published. Users are advised to switch to the new UCXX project.

Impact

Development for the UCX-Py repository will cease and no new packages will be published. UCX-Py will be dropped from the rapids conda metapackage and RAPIDS Docker containers.

Continued accelerated communication support

Dask-CUDA and Dask/Distributed users may continue to benefit from UCX support through the new UCXX project. Python developers will continue to be supported as well. Additionally, UCXX now provides a C++ library to interface with UCX.

Dask-CUDA

Dask-CUDA users have been automatically migrated. Beginning with RAPIDS v25.08, if the distributed-ucxx package is installed, setting protocol="ucx" will now automatically use UCXX instead of UCX-Py. If distributed-ucxx is not installed the old UCX-Py will still be be used and a warning will be emitted to advise updating. Setting protocol="ucxx" always uses UCXX and will continue to work. In RAPIDS v25.08 users can still continue to use UCX-Py by setting protocol="ucx-old", but this option will be removed in RAPIDS v25.10.

Dask/Distributed

Dask/Distributed will require installing the distributed-ucxx package and setting protocol="ucxx". After the migration is completed, protocol="ucx" will also use UCXX, provided the distributed-ucxx package is installed.

Python developers

Python developers who directly used UCX-Py via import ucp will continue to be supported via import ucxx, this requires the ucxx package to be installed. There may be minor changes, users are advised to consult the API documentation.

C++

With the introduction of UCXX, C++ developers can also benefit from a proper C++ library to interface with UCX via the new libucxx package, providing a RAII interface along with additional features.