How can I use MPI?

[LAZY1764]

The documentation of ALPS states :
To run the simulation on a parallel machine using MPI, call the following command instead: pyalps.runApplication('spinmc',input_file,Tmin=5,writexml=True,MPI=4)
But when I set MPI parameter and run pyalps.runApplication, my code failed "This program has not been compiled for use with MPI".

I had followed the youtube video of ALPS and install pyalps in WSL Ubuntu.

[Ooolab]

The binary installation is only serial. To have a parallel version of ALPS, you would need to do the source installation. Please check out the page: https://alps.comp-phys.org/documentation/install/source/

Make sure that MPI is installed before you run the step 3 (cmake)
The build command: "cmake --build alps-build -j 8" specifies a parallel compilation.

After your installation from source, you should be able to run your parallel "spinmc".

[LAZY1764]

I failed to do source installation AT STEP3("cmake -S alps-src -B alps-build"). The error code is as following:
CMake Error at /usr/share/cmake-3.28/Modules/FindPackageHandleStandardArgs.cmake:230 (message): Could NOT find Python (missing: Python_EXECUTABLE Python_INCLUDE_DIRS Python_LIBRARIES Interpreter Development Development.Module Development.Embed) Call Stack (most recent call first): /usr/share/cmake-3.28/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE) /usr/share/cmake-3.28/Modules/FindPython.cmake:616 (find_package_handle_standard_args) config/FindPythonMod.cmake:64 (find_package) CMakeLists.txt:231 (find_package)
GCC version: 13.3.0, cmake version: 3.28.3, MPIrun version: 4.1.6.

I had tried to run this command :
with and without venv,
python3.12 and python3.9,
set and not set "-DPython3_EXECUTABLE=/usr/bin/python3.9",
but the error code is the same.

[Ooolab]

Hello, My suggestion would be removing the previous Python and reinstalling the Python. And for the dependencies of ALPS, please compile them with the same Python version. Mixing different versions of Python could cause the problem.

[Ooolab]

meant: dependency libraries

[LAZY1764]

So I can't install pyalps from source with python3.12 ? I can't remove it since it is the pre-installed system dependency for Ubuntu 24.04.

[Ooolab]

You can use Python 3.12. But you need to make sure other dependencies, such as Numpy etc were also installed with 3.12 and not 3.9.

[LAZY1764]

At first, there is only python3.12 in my wsl. It was after I guessed python3.12 maybe too new to install pyalps that I installed python3.9.

[Ooolab]

Python3.12 works perfectly with the source installation.

[LAZY1764]

I have successfully installed the MPI version via spack.
https://alps.comp-phys.org/zh-cn/documentation/install/spack/

[Ooolab]

Good to know spack installation works for you!
To run MPI, in your Python script invoke the ALPS run with a similar statement like the following:
res = pyalps.runApplication('sparsediag',input_file, MPI=4, mpirun='mpirun')

instead of the following for serial run:
res = pyalps.runApplication('sparsediag',input_file)

Or you can do the following:
parameter2xml parm job
mpirun -np 4 my_program --mpi job.in.xml

where you first generate an input file, and "my_program" is for example "sparsediag" in the above example.

Here is the page for running ALPS:
https://alps.comp-phys.org/documentation/intro/runalps/commandline/