Installing Ray¶

Ray currently supports MacOS and Linux. Windows wheels are now available, but Windows support is experimental and under development.

Official Releases¶

You can install the latest official version of Ray as follows. Official releases are produced according to the release process doc.

pip install -U ray  # minimal install

# To install Ray with support for the dashboard + cluster launcher, run
# `pip install -U 'ray[default]'`

To install Ray libraries:

pip install -U ray[tune]  # installs Ray + dependencies for Ray Tune
pip install -U ray[rllib]  # installs Ray + dependencies for Ray RLlib
pip install -U ray[serve]  # installs Ray + dependencies for Ray Serve

Note for Windows Users: To use Ray on Windows, Visual C++ runtime must be installed (see Windows Dependencies section). If you run into any issues, please see the Windows Support section.

Daily Releases (Nightlies)¶

You can install the nightly Ray wheels via the following links. These daily releases are tested via automated tests but do not go through the full release process. To install these wheels, use the following pip command and wheels:

pip install -U LINK_TO_WHEEL.whl  # minimal install

# To install Ray with support for the dashboard + cluster launcher, run
# `pip install -U 'ray[default]' @ LINK_TO_WHEEL.whl`

Linux	MacOS	Windows (experimental)
Linux Python 3.9	MacOS Python 3.9	Windows Python 3.9
Linux Python 3.8	MacOS Python 3.8	Windows Python 3.8
Linux Python 3.7	MacOS Python 3.7	Windows Python 3.7
Linux Python 3.6	MacOS Python 3.6	Windows Python 3.6

Note

Python 3.9 support is currently experimental.

Installing from a specific commit¶

You can install the Ray wheels of any particular commit on master with the following template. You need to specify the commit hash, Ray version, Operating System, and Python version:

pip install https://s3-us-west-2.amazonaws.com/ray-wheels/master/{COMMIT_HASH}/ray-{RAY_VERSION}-{PYTHON_VERSION}-{PYTHON_VERSION}m-{OS_VERSION}.whl

For example, here are the Ray 2.0.0.dev0 wheels for Python 3.7, MacOS for commit ba6cebe30fab6925e5b2d9e859ad064d53015246:

pip install https://s3-us-west-2.amazonaws.com/ray-wheels/master/ba6cebe30fab6925e5b2d9e859ad064d53015246/ray-2.0.0.dev0-cp37-cp37m-macosx_10_15_intel.whl

There are minor variations to the format of the wheel filename; it’s best to match against the format in the URLs listed in the Nightlies section. Here’s a summary of the variations:

For Python 3.8 and 3.9, the m before the OS version should be deleted and the OS version for MacOS should read macosx_10_15_x86_64 instead of macosx_10_15_intel.
For MacOS, commits predating August 7, 2021 will have macosx_10_13 in the filename instad of macosx_10_15.

Install Ray Java with Maven¶

Before installing Ray Java with Maven, you should install Ray Python with pip install -U ray . Note that the versions of Ray Java and Ray Python must match. Note that nightly Ray python wheels are also required if you want to install Ray Java snapshot version.

The latest Ray Java release can be found in central repository. To use the latest Ray Java release in your application, add the following entries in your pom.xml:

<dependency>
  <groupId>io.ray</groupId>
  <artifactId>ray-api</artifactId>
  <version>${ray.version}</version>
</dependency>
<dependency>
  <groupId>io.ray</groupId>
  <artifactId>ray-runtime</artifactId>
  <version>${ray.version}</version>
</dependency>

The latest Ray Java snapshot can be found in sonatype repository. To use the latest Ray Java snapshot in your application, add the following entries in your pom.xml:

<!-- only needed for snapshot version of ray -->
<repositories>
  <repository>
    <id>sonatype</id>
    <url>https://oss.sonatype.org/content/repositories/snapshots/</url>
    <releases>
      <enabled>false</enabled>
    </releases>
    <snapshots>
      <enabled>true</enabled>
    </snapshots>
  </repository>
</repositories>

<dependencies>
  <dependency>
    <groupId>io.ray</groupId>
    <artifactId>ray-api</artifactId>
    <version>${ray.version}</version>
  </dependency>
  <dependency>
    <groupId>io.ray</groupId>
    <artifactId>ray-runtime</artifactId>
    <version>${ray.version}</version>
  </dependency>
</dependencies>

Note

When you run pip install to install Ray, Java jars are installed as well. The above dependencies are only used to build your Java code and to run your code in local mode.

If you want to run your Java code in a multi-node Ray cluster, it’s better to exclude Ray jars when packaging your code to avoid jar conficts if the versions (installed Ray with pip install and maven dependencies) don’t match.

Windows Support¶

Windows support is currently limited and “alpha” quality. Bugs, process/resource leaks, or other incompatibilities may exist under various scenarios. Unusual, unattended, or production usage is not recommended.

To use Ray on Windows, the Visual C++ runtime must be installed (see Windows Dependencies section).

If you encounter any issues, please try the following:

Check the Windows Known Issues page on GitHub to see the latest updates on Windows support.
In the case that your issue has been addressed, try installing the latest nightly wheels.

If your issue has not yet been addressed, comment on the Windows Known Issues page.

Windows Dependencies¶

For Windows, ensure the latest Visual C++ runtime (install link) is installed before using Ray.

Otherwise, you may receive an error similar to the following when Ray fails to find the runtime library files (e.g. VCRUNTIME140_1.dll):

FileNotFoundError: Could not find module '_raylet.pyd' (or one of its dependencies).

Installing Ray on Arch Linux¶

Note: Installing Ray on Arch Linux is not tested by the Project Ray developers.

Ray is available on Arch Linux via the Arch User Repository (AUR) as python-ray.

You can manually install the package by following the instructions on the Arch Wiki or use an AUR helper like yay (recommended for ease of install) as follows:

yay -S python-ray

To discuss any issues related to this package refer to the comments section on the AUR page of python-ray here.

Installing Ray with Anaconda¶

If you use Anaconda (installation instructions) and want to use Ray in a defined environment, e.g, ray, use these commands:

conda create --name ray
conda activate ray
conda install --name ray pip
pip install ray

Use pip list to confirm that ray is installed.

Building Ray from Source¶

Installing from pip should be sufficient for most Ray users.

However, should you need to build from source, follow these instructions for building Ray.

Docker Source Images¶

Most users should pull a Docker image from the Ray Docker Hub.

The rayproject/ray image has ray and all required dependencies. It comes with anaconda and Python 3.7.
The rayproject/ray-ml image has the above features as well as many additional libraries.
The rayproject/base-deps and rayproject/ray-deps are for the linux and python dependencies respectively.

Image releases are tagged using the following format:

Tag	Description
latest	The most recent Ray release.
1.x.x	A specific Ray release.
nightly	The most recent Ray build (the most recent commit on Github `master`)
Git SHA	A specific nightly build (uses a SHA from the Github `master`).

Each tag has variants that add or change functionality:

Variant	Description
-gpu	These are based off of an NVIDIA CUDA image. They require the Nvidia Docker Runtime.
-cpu	These are based off of an Ubuntu image.
<no tag>	Aliases to `-cpu` tagged images

If you want to tweak some aspect of these images and build them locally, refer to the following script:

cd ray
./build-docker.sh

Beyond creating the above Docker images, this script can also produce the following two images.

The rayproject/development image has the ray source code included and is setup for development.
The rayproject/examples image adds additional libraries for running examples.

Review images by listing them:

docker images

Output should look something like the following:

REPOSITORY                          TAG                 IMAGE ID            CREATED             SIZE
rayproject/ray                      latest              7243a11ac068        2 days ago          1.11 GB
rayproject/ray-deps                 latest              b6b39d979d73        8 days ago          996  MB
rayproject/base-deps                latest              5606591eeab9        8 days ago          512  MB
ubuntu                              focal               1e4467b07108        3 weeks ago         73.9 MB

Launch Ray in Docker¶

Start out by launching the deployment container.

docker run --shm-size=<shm-size> -t -i rayproject/ray

Replace <shm-size> with a limit appropriate for your system, for example 512M or 2G. A good estimate for this is to use roughly 30% of your available memory (this is what Ray uses internally for its Object Store). The -t and -i options here are required to support interactive use of the container.

If you use a GPU version Docker image, remember to add --gpus all option. Replace <ray-version> with your target ray version in the following command:

docker run --shm-size=<shm-size> -t -i --gpus all rayproject/ray:<ray-version>-gpu

Note: Ray requires a large amount of shared memory because each object store keeps all of its objects in shared memory, so the amount of shared memory will limit the size of the object store.

You should now see a prompt that looks something like:

root@ebc78f68d100:/ray#

Test if the installation succeeded¶

To test if the installation was successful, try running some tests. This assumes that you’ve cloned the git repository.

python -m pytest -v python/ray/tests/test_mini.py

Troubleshooting¶

If importing Ray (python3 -c "import ray") in your development clone results in this error:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File ".../ray/python/ray/__init__.py", line 63, in <module>
    import ray._raylet  # noqa: E402
  File "python/ray/_raylet.pyx", line 98, in init ray._raylet
    import ray.memory_monitor as memory_monitor
  File ".../ray/python/ray/memory_monitor.py", line 9, in <module>
    import psutil  # noqa E402
  File ".../ray/python/ray/thirdparty_files/psutil/__init__.py", line 159, in <module>
    from . import _psosx as _psplatform
  File ".../ray/python/ray/thirdparty_files/psutil/_psosx.py", line 15, in <module>
    from . import _psutil_osx as cext
ImportError: cannot import name '_psutil_osx' from partially initialized module 'psutil' (most likely due to a circular import) (.../ray/python/ray/thirdparty_files/psutil/__init__.py)

Then you should run the following commands:

rm -rf python/ray/thirdparty_files/
python3 -m pip install setproctitle

Ray v2.0.0.dev0