PyNumero and Parapint

This archive is distributed in association with the INFORMS Journal on Computing under the BSD 3-Clause License.

The software and data in this repository are a snapshot of the software and data that were used in the research reported on in the paper Scalable Parallel Nonlinear Optimization with PyNumero and Parapint by J. Rodriguez, R. Parker, C. Laird, B. Nicholson, J. Siirola, and M. Bynum. Note that PyNumero is a module within Pyomo. The snapshot is based on this SHA for PyNumero and this SHA for Parapint in their respective development repositories.

Important: This code is being developed on an on-going basis at https://github.com/Pyomo/pyomo/tree/main/pyomo/contrib/pynumero and at https://github.com/Parapint/parapint. Please go there if you would like to get a more recent version or would like support.

Cite

To cite this software, please cite the paper using its DOI and the software itself using the following DOI:

Below is the BibTex for citing this version of the code.

@misc{Parapint,
  author =        {Bynum, Michael and Laird, Carl and Nicholson, Bethany and Rizdal, Denis},
  publisher =     {INFORMS Journal on Computing},
  title =         {{Parapint} Version v2021.0285},
  year =          {2022},
  doi =           {10.5281/zenodo.7192328},
  url =           {https://github.com/INFORMSJoC/2021.0285},
}  

Description

PyNumero is a package for developing parallel algorithms for nonlinear programs (NLPs). Documentation can be found at https://pyomo.readthedocs.io/en/stable/contributed_packages/pynumero/index.html.

Parapint is a Python package for parallel solution of structured nonlinear programs. Documentation can be found at https://parapint.readthedocs.io/en/latest/.

Requirements

The following prerequisites must be installed prior to using the code in this repository.

• Python: https://www.python.org (we used version 3.9.5)
• Open MPI: https://www.open-mpi.org (we used version 2.1.1)
• MPI for Python: https://github.com/mpi4py/mpi4py (we used version 3.0.3)
• NumPy: https://github.com/numpy/numpy (we used version 1.21.2)
• SciPy: https://github.com/scipy/scipy (we used version 1.7.1)
• Plotly: https://plotly.com (we used version 5.9.0)
• Matplotlib: https://matplotlib.org (we used version 3.5.2)
• Ipopt: https://coin-or.github.io/Ipopt (we used version 3.12.5). Note that Ipopt needs to be installed from source with shared libraries for ASL and HSL MA27.

Installation

Note that these installation instructions should work on Linux and OSX. Windows has not been tested.

First, Pyomo must be installed from source:

git clone https://github.com/pyomo/pyomo.git
cd pyomo
git checkout -b v6.4.1 6.4.1
pip install -e ./

Next, the PyNumero extensions need built:

cd pyomo/contrib/pynumero/
python build.py -DBUILD_ASL=ON -DBUILD_MA27=ON -DIPOPT_DIR=<path/to/ipopt/build/>

If these steps succeed, PyNumero should work.

Finally, Parapint can be installed from this repository. Be sure to navigate out of the Pyomo directory first.

git clone https://github.com/INFORMSJoC/2021.0285.git IJOC_2021.0285
cd IJOC_2021.0285/src/
pip install -e ./

Results

Figure 3 in the paper shows weak scaling for PyNumero's parallel matrix-vector dot product.

Figure 4 in the paper shows weak scaling for the solution of structured linear systems using Parapint's Schur-Complement decomposition method.

Figure 5 in the paper shows scaling results for Parapint's interior-point algorithm applied to 2-dimensional PDE-constrainted optimal control problem with Burgers' Equation.

Replicating Results from the Paper

Section 2.4 - SQP

cd scripts
python sqp.py --nfe_x 500 --nfe_t 1000

Section 4 - Weak Scaling of Matrix-Vector Dot Products

cd scripts/parallel_matrix_vector_product
mpirun -np 8 python -m mpi4py weak_scaling.py
mpirun -np 16 python -m mpi4py weak_scaling.py
mpirun -np 32 python -m mpi4py weak_scaling.py
...
python plot_results.py

Section 4 - Weak Scaling of Schur-Complement Decomposition

cd scripts/schur_complement
mpirun -np 8 python -m mpi4py main.py --method psc --n_blocks 8
mpirun -np 16 python -m mpi4py main.py --method psc --n_blocks 16
mpirun -np 32 python -m mpi4py main.py --method psc --n_blocks 32
...
python plot_results.py

Section 4 - Parallel Interior-Point Performance

python burgers.py --nfe_x 30 --end_t 2 --nfe_t_per_t 1600 --nblocks 1 --method fs
python burgers.py --nfe_x 30 --end_t 4 --nfe_t_per_t 1600 --nblocks 1 --method fs
python burgers.py --nfe_x 30 --end_t 8 --nfe_t_per_t 1600 --nblocks 1 --method fs
...
mpirun -np 2 python -m mpi4py burgers.py --nfe_x 30 --end_t 2 --nfe_t_per_t 1600 --nblocks 2 --method psc
mpirun -np 4 python -m mpi4py burgers.py --nfe_x 30 --end_t 4 --nfe_t_per_t 1600 --nblocks 4 --method psc
mpirun -np 8 python -m mpi4py burgers.py --nfe_x 30 --end_t 8 --nfe_t_per_t 1600 --nblocks 8 --method psc
...
python make_plots.py