Install and Setup
=================

System requirements
-------------------
DGL works with the following operating systems:

* Ubuntu 16.04
* macOS X
* Windows 10

DGL requires Python version 3.6, 3.7, 3.8 or 3.9.

DGL supports multiple tensor libraries as backends, e.g., PyTorch, MXNet. For requirements on backends and how to select one, see :ref:`backends`.

Starting at version 0.3, DGL is separated into CPU and CUDA builds.  The builds share the
same Python package name. If you install DGL with a CUDA 9 build after you install the
CPU build, then the CPU build is overwritten.

Install from Conda or Pip
-------------------------

We recommend installing DGL by ``conda`` or ``pip``.
Check out the instructions on the `Get Started page <https://www.dgl.ai/pages/start.html>`_.

.. note::

   For Windows users: you will need to install `Visual C++ 2015 Redistributable <https://www.microsoft.com/en-us/download/details.aspx?id=48145>`_.

.. _install-from-source:

Install from source
-------------------
Download the source files from GitHub.

.. code:: bash

   git clone --recurse-submodules https://github.com/dmlc/dgl.git

(Optional) Clone the repository first, and then run the following:

.. code:: bash

   git submodule update --init --recursive

Linux
`````

Install the system packages for building the shared library. For Debian and Ubuntu
users, run:

.. code:: bash

   sudo apt-get update
   sudo apt-get install -y build-essential python3-dev make cmake

For Fedora/RHEL/CentOS users, run:

.. code:: bash

   sudo yum install -y gcc-c++ python3-devel make cmake

Build the shared library. Use the configuration template ``cmake/config.cmake``.
Copy it to either the project directory or the build directory and change the
configuration as you wish. For example, change ``USE_CUDA`` to ``ON`` will
enable a CUDA build. You could also pass ``-DKEY=VALUE`` to the cmake command
for the same purpose.

* CPU-only build::

     mkdir build
     cd build
     cmake ..
     make -j4

* CUDA build::

     mkdir build
     cd build
     cmake -DUSE_CUDA=ON ..
     make -j4

Finally, install the Python binding.

.. code:: bash

   cd ../python
   python setup.py install

macOS
`````

Installation on macOS is similar to Linux. But macOS users need to install build tools like clang, GNU Make, and cmake first. These installation steps were tested on macOS X with clang 10.0.0, GNU Make 3.81, and cmake 3.13.1.

Tools like clang and GNU Make are packaged in **Command Line Tools** for macOS. To
install, run the following:

.. code:: bash

   xcode-select --install

To install other needed packages like cmake, we recommend first installing
**Homebrew**, which is a popular package manager for macOS. To learn more, see the `Homebrew website <https://brew.sh/>`_.

After you install Homebrew, install cmake.

.. code:: bash

   brew install cmake

Go to root directory of the DGL repository, build a shared library, and
install the Python binding for DGL.

.. code:: bash

   mkdir build
   cd build
   cmake -DUSE_OPENMP=off -DCMAKE_C_FLAGS='-DXBYAK_DONT_USE_MAP_JIT' -DCMAKE_CXX_FLAGS='-DXBYAK_DONT_USE_MAP_JIT' -DUSE_AVX=OFF -DUSE_LIBXSMM=OFF ..
   make -j4
   cd ../python
   python setup.py install

Windows
```````

You can build DGL with MSBuild.  With `MS Build Tools <https://go.microsoft.com/fwlink/?linkid=840931>`_
and `CMake on Windows <https://cmake.org/download/>`_ installed, run the following
in VS2019 x64 Native tools command prompt.

* CPU only build::

     MD build
     CD build
     cmake -DCMAKE_CXX_FLAGS="/DDGL_EXPORTS" -DCMAKE_CONFIGURATION_TYPES="Release" -DDMLC_FORCE_SHARED_CRT=ON .. -G "Visual Studio 16 2019"
     msbuild dgl.sln /m
     CD ..\python
     python setup.py install

* CUDA build::

     MD build
     CD build
     cmake -DCMAKE_CXX_FLAGS="/DDGL_EXPORTS" -DCMAKE_CONFIGURATION_TYPES="Release" -DDMLC_FORCE_SHARED_CRT=ON -DUSE_CUDA=ON .. -G "Visual Studio 16 2019"
     msbuild dgl.sln /m
     CD ..\python
     python setup.py install

Compilation Flags
`````````````````

See `config.cmake <https://github.com/dmlc/dgl/blob/master/cmake/config.cmake>`_.


.. _backends:

Working with different backends
-------------------------------

DGL supports PyTorch, MXNet and Tensorflow backends. 
DGL will choose the backend on the following options (high priority to low priority)

* Use the ``DGLBACKEND`` environment variable:

   - You can use ``DGLBACKEND=[BACKEND] python gcn.py ...`` to specify the backend
   - Or ``export DGLBACKEND=[BACKEND]`` to set the global environment variable 

* Modify the ``config.json`` file under "~/.dgl":

   - You can use ``python -m dgl.backend.set_default_backend [BACKEND]`` to set the default backend

Currently BACKEND can be chosen from mxnet, pytorch, tensorflow.

PyTorch backend
```````````````

Export ``DGLBACKEND`` as ``pytorch`` to specify PyTorch backend. The required PyTorch
version is 1.5.0 or later. See `pytorch.org <https://pytorch.org>`_ for installation instructions.

MXNet backend
`````````````

Export ``DGLBACKEND`` as ``mxnet`` to specify MXNet backend. The required MXNet version is
1.5 or later. See `mxnet.apache.org <https://mxnet.apache.org/get_started>`_ for installation
instructions.

MXNet uses uint32 as the default data type for integer tensors, which only supports graph of
size smaller than 2^32. To enable large graph training, *build* MXNet with ``USE_INT64_TENSOR_SIZE=1``
flag. See `this FAQ <https://mxnet.apache.org/api/faq/large_tensor_support>`_ for more information.

MXNet 1.5 and later has an option to enable Numpy shape mode for ``NDArray`` objects, some DGL models
need this mode to be enabled to run correctly. However, this mode may not compatible with pretrained
model parameters with this mode disabled, e.g. pretrained models from GluonCV and GluonNLP.
By setting ``DGL_MXNET_SET_NP_SHAPE``, users can switch this mode on or off.

Tensorflow backend
``````````````````

Export ``DGLBACKEND`` as ``tensorflow`` to specify Tensorflow backend. The required Tensorflow
version is 2.2.0 or later. See `tensorflow.org <https://www.tensorflow.org/install>`_ for installation
instructions. In addition, DGL will set ``TF_FORCE_GPU_ALLOW_GROWTH`` to ``true`` to prevent Tensorflow take over the whole GPU memory:

.. code:: bash

   pip install "tensorflow>=2.2.0"  # when using tensorflow cpu version

