DCBC: solve a MILP problem with a distributed set of CBC solver instances

CBC is a free open-source MILP solver from the COIN-OR suite
(https://projects.coin-or.org/Cbc). DCBC is an Erlang-based system managing
a set of CBC solver instances running together on a set of subproblems generated
from a single MILP problem.


Executables

c_src/cbc_port
A port program for communicating with CBC from Erlang.

c_src/cbc_port
A port program for communicating with SCIP from Erlang.

c_src/nlmod
A program for splitting a problem, encoded as AMPL stub, to a set of subproblems.

registry.sh
Starts an Erlang node managing registration of slave nodes. Only one registry
node should be started. Its node@host should be set in the registry-node file.

slave.sh [number of cpu]
Starts an Erlang node which starts CBC solver instances. It should be started
one per host.

master.sh [solver options <-->] <list of .nl files of subproblems>
Solve a set of subproblems on all available slave nodes found in registry.

solve.sh [solver options <-->] <list of .nl files of subproblems>
Same as master.sh but exits after solving the last subproblem.


Installation

1. Install CBC and Erlang.
   
https://www.erlang-solutions.com/downloads/download-erlang-otp

2. On the command line:
git clone https://github.com/ssmir/dcbc.git
cd dcbc
./bootstrap.sh
make

If you wish to use SCIP:
Copy reader_nl.h and reader_nl.c from interfaces/ampl/src in SCIP source tree
to dcbc/c_src. Then, if SCIP libraries are installed in /usr/local/lib and
SCIP headers are in /usr/local/include:
make USE_SCIP=true SCIP_HOME=/usr/local

If it doesn't compile, also add SCIP_LIBS=<libraries needed to link with SCIP>
to make command line

3. Erlang cookie file ~/.erlang.cookie have to be same on every node working
with DCBC


Usage

1. Edit registry-node file. It has to contain the name of the registry node with
an IP address reachable from other nodes, for example:
[email protected]

2. Start the registry node on the machine with the address specified
in the registry-node file:
./registry.sh

3. Start slave nodes on every machine used for computations.
./slave.sh

It's possible to specify the maximum number of solver processes running
simultaneously:
./slave 5
would run maximum 5 processes

4. Solve some problems with solve.sh:
./solve.sh 1.nl 2.nl 3.nl


Shutting down:

It's possible to shut down a node running on the local machine:
./stop-node.sh slave
./stop-node.sh registry


External dependencies

AMPL solver library (http://www.netlib.org/ampl/solvers/ or https://github.com/ampl/ampl)
ASL util library by Victor Zverovich (https://github.com/ampl/ampl)
CBC (https://projects.coin-or.org/Cbc)
SCIP (http://scip.zib.de/)
Erlang (http://www.erlang.org)