libucxx-cu12

0.49.0 verified Fri May 01 auth: no python

Python Bindings for the Unified Communication X library (UCX), including CUDA 12 support. Provides high-performance communication primitives for distributed computing, commonly used in RAPIDS ecosystem. Current version: 0.49.0, part of the RAPIDS suite, released monthly.

pip install libucxx-cu12

Common errors

error ModuleNotFoundError: No module named 'ucp' ↓

cause Installed libucxx-cu12 but expected import name differs.

fix

Use import ucp — the package installs the ucp module.

error RuntimeError: UCX library not found ↓

cause The underlying UCX system library is missing or not in LD_LIBRARY_PATH.

fix

Install UCX system package (e.g., apt-get install libucx-dev) or set LD_LIBRARY_PATH.

error ImportError: libcuda.so.1: cannot open shared object file ↓

cause CUDA runtime not found; likely CUDA is not installed or LD_LIBRARY_PATH not set.

fix

Install CUDA 12.2+ and ensure LD_LIBRARY_PATH includes CUDA lib64.

error AssertionError: UCX version >= 1.12.0 required ↓

cause The installed UCX system library is outdated.

fix

Update UCX to version 1.12.0 or higher (e.g., via conda or from source).

Warnings

gotcha The PyPI package name is `libucxx-cu12` but the import is `ucp`. Installing libucxx-cu12 provides the `ucp` Python module. ↓

fix Import as `import ucp`.

breaking Version 0.49.0 removed the numba-cuda runtime dependency in favor of cuda-core. Code relying on numba-cuda interop may need updates. ↓

fix If you use numba-cuda with UCX, switch to cuda-core based API.

breaking Version 0.47.0 requires CUDA 12.2+. Systems with older CUDA will encounter compatibility issues. ↓

fix Update CUDA to 12.2 or later, or pin to an older libucxx-cu12 version.

gotcha The package name includes '-cu12' which is specific to CUDA 12. For CUDA 11, use 'libucxx-cu11'. ↓

fix Ensure you install the correct variant matching your CUDA version.

deprecated The `ucp` module is the recommended interface. Some older docs reference `ucxx` directly. ↓

fix Use `import ucp` instead of `import ucxx`.

Imports

UCXListener
wrong
```
from libucxx import UCXListener
```
correct
```
from ucp import UCXListener
```
libucxx-cu12 is not the direct import; the Python bindings are typically accessed via the 'ucp' package.
ucp.init
wrong
```
from libucxx import ucp
```
correct
```
import ucp
```
The UCX Python bindings are published as the 'ucp' package.

Quickstart

Quickstart example using UCX-Py (the Python bindings). Note: libucxx-cu12 is the CUDA 12 variant; actual usage is via the `ucp` module.

import ucp

async def server(ep):
    msg = await ep.recv(1024)
    print(f"Received: {msg}")
    await ep.send(b"pong")

async def main():
    listener = ucp.create_listener(server, port=13337)
    ep = await ucp.create_endpoint(ucp.get_address(), 13337)
    await ep.send(b"ping")
    reply = await ep.recv(1024)
    print(f"Reply: {reply}")
    listener.close()

ucp.init()
ucp.get_worker().run()