[docs] documented version without OpenMP support

docs/Installation-Guide.rst

@@ -15,6 +15,8 @@ For the build of Python-package and R-package, please refer to `Python-package`_
 
 -  `Docker <#docker>`__
 
+- `Threadless Version (not Recommended) <#build-threadless-version-not-recommended>`__
+
 -  `MPI Version <#build-mpi-version>`__
 
 -  `GPU Version <#build-gpu-version>`__
@@ -177,6 +179,151 @@ Docker
 
 Refer to `Docker folder <https://github.com/Microsoft/LightGBM/tree/master/docker>`__.
 
+Build Threadless Version (not Recommended)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The default build version of LightGBM is based on OpenMP.
+However, you can build the LightGBM without OpenMP support, but it is **strongly not recommended**.
+
+Windows
+^^^^^^^
+
+On Windows version of LightGBM without OpenMP support can be built using
+
+- **Visual Studio**;
+
+- **CMake** and **VS Build Tools**;
+
+- **CMake** and **MinGW**.
+
+Visual Studio (or VS Build Tools)
+*********************************
+
+With GUI
+--------
+
+1. Install `Visual Studio`_ (2015 or newer).
+
+2. Download `zip archive`_ and unzip it.
+
+3. Go to ``LightGBM-master/windows`` folder.
+
+4. Open ``LightGBM.sln`` file with **Visual Studio**.
+
+5. Go to ``PROJECT`` -> ``Properties`` -> ``Configuration Properties`` -> ``C/C++`` -> ``Language`` and change the ``OpenMP Support`` property to ``No (/openmp-)``.
+
+6. Get back to the project's main screen, then choose ``Release`` configuration and click ``BUILD`` -> ``Build Solution (Ctrl+Shift+B)``.
+
+   If you have errors about **Platform Toolset**, go to ``PROJECT`` -> ``Properties`` -> ``Configuration Properties`` -> ``General`` and select the toolset installed on your machine.
+
+The exe file will be in ``LightGBM-master/windows/x64/Release`` folder.
+
+From Command Line
+-----------------
+
+1. Install `Git for Windows`_, `CMake`_ (3.8 or higher) and `VS Build Tools`_ (**VS Build Tools** is not needed if **Visual Studio** (2015 or newer) is already installed).
+
+2. Run the following commands:
+
+   .. code::
+
+     git clone --recursive https://github.com/Microsoft/LightGBM
+     cd LightGBM
+     mkdir build
+     cd build
+     cmake -DCMAKE_GENERATOR_PLATFORM=x64 -DUSE_OPENMP=OFF ..
+     cmake --build . --target ALL_BUILD --config Release
+
+The exe and dll files will be in ``LightGBM/Release`` folder.
+
+MinGW-w64
+*********
+
+1. Install `Git for Windows`_, `CMake`_ and `MinGW-w64`_.
+
+2. Run the following commands:
+
+   .. code::
+
+     git clone --recursive https://github.com/Microsoft/LightGBM
+     cd LightGBM
+     mkdir build
+     cd build
+     cmake -G "MinGW Makefiles" -DUSE_OPENMP=OFF ..
+     mingw32-make.exe -j4
+
+The exe and dll files will be in ``LightGBM/`` folder.
+
+**Note**: You may need to run the ``cmake -G "MinGW Makefiles" -DUSE_OPENMP=OFF ..`` one more time if you encounter the ``sh.exe was found in your PATH`` error.
+
+Linux
+^^^^^
+
+On Linux version of LightGBM without OpenMP support can be built using **CMake** and **gcc** or **Clang**.
+
+1. Install `CMake`_.
+
+2. Run the following commands:
+
+   .. code::
+
+     git clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBM
+     mkdir build ; cd build
+     cmake -DUSE_OPENMP=OFF ..
+     make -j4
+
+**Note**: glibc >= 2.14 is required.
+
+macOS
+^^^^^
+
+On macOS version of LightGBM without OpenMP support can be built using **CMake** and **Apple Clang** or **gcc**.
+
+Apple Clang
+***********
+
+Only **Apple Clang** version 8.1 or higher is supported.
+
+1. Install `CMake`_ (3.12 or higher):
+
+   .. code::
+
+     brew install cmake
+
+2. Run the following commands:
+
+   .. code::
+
+     git clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBM
+     mkdir build ; cd build
+     cmake -DUSE_OPENMP=OFF ..
+     make -j4
+
+gcc
+***
+
+1. Install `CMake`_ (3.2 or higher):
+
+   .. code::
+
+     brew install cmake
+
+2. Install **gcc**:
+
+   .. code::
+
+     brew install gcc
+
+3. Run the following commands:
+
+   .. code::
+
+     git clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBM
+     export CXX=g++-7 CC=gcc-7  # replace "7" with version of gcc installed on your machine
+     mkdir build ; cd build
+     cmake -DUSE_OPENMP=OFF ..
+     make -j4
+
 Build MPI Version
 ~~~~~~~~~~~~~~~~~
 

docs/_static/js/script.js

@@ -6,7 +6,8 @@ $(function() {
     /* Collapse specified sections in the installation guide */
     if(window.location.pathname.toLocaleLowerCase().indexOf('installation-guide') != -1) {
         $('<style>.closed, .opened {cursor: pointer;} .closed:before, .opened:before {font-family: FontAwesome; display: inline-block; padding-right: 6px;} .closed:before {content: "\\f078";} .opened:before {content: "\\f077";}</style>').appendTo('body');
-        var collapsable = ['#build-mpi-version', '#build-gpu-version', '#build-hdfs-version', '#build-java-wrapper'];
+        var collapsable = ['#build-threadless-version-not-recommended', '#build-mpi-version', '#build-gpu-version',
+                           '#build-hdfs-version', '#build-java-wrapper'];
         $.each(collapsable, function(i, val) {
             var header = val + ' > :header:first';
             var content = val + ' :not(:header:first)';

python-package/README.rst

@@ -47,6 +47,17 @@ For **macOS** users, you can perform installation either with **Apple Clang** or
 
 For **Windows** users, **Visual Studio** (or `VS Build Tools <https://visualstudio.microsoft.com/downloads/>`_) is needed. If you get any errors during installation, you may need to install `CMake`_ (version 3.8 or higher).
 
+Build Threadless Version
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. code:: sh
+
+    pip install lightgbm --install-option=--nomp
+
+All remarks, except the **OpenMP** requirement for macOS users, from `Build from Sources section <#build-from-sources>`__ are actual in this case.
+
+It is **strongly not recommended** to use this version of LightGBM!
+
 Build MPI Version
 ~~~~~~~~~~~~~~~~~
 
@@ -129,6 +140,8 @@ For **Windows** users, if you get any errors during installation and there is th
 
 Note: ``sudo`` (or administrator rights in **Windows**) may be needed to perform the command.
 
+Run ``python setup.py install --nomp`` to disable **OpenMP** support. All remarks from `Build Threadless Version section <#build-threadless-version>`__ are actual in this case.
+
 Run ``python setup.py install --mpi`` to enable **MPI** support. All remarks from `Build MPI Version section <#build-mpi-version>`__ are actual in this case.
 
 Run ``python setup.py install --mingw``, if you want to use **MinGW-w64** on **Windows** instead of **Visual Studio**. All remarks from `Build with MinGW-w64 on Windows section <#build-with-mingw-w64-on-windows>`__ are actual in this case.

python-package/setup.py

@@ -186,7 +186,7 @@ class CustomInstall(install):
         ('mingw', 'm', 'Compile with MinGW'),
         ('gpu', 'g', 'Compile GPU version'),
         ('mpi', None, 'Compile MPI version'),
-        ('nomp', None, 'Compile without openmp'),
+        ('nomp', None, 'Compile version without OpenMP support'),
         ('hdfs', 'h', 'Compile HDFS version'),
         ('precompile', 'p', 'Use precompiled library'),
         ('boost-root=', None, 'Boost preferred installation prefix'),