Large-scale 0-1 Linear Programming on Distributed Workstations

We present a methodology which uses a collection of workstations connected by an Ethernet network as a parallel processor for solving large-scale linear programming problems. On the largest problems we tested, linear and super-linear speedups have been achieved. Using the "branch-and-cut" approach of Hoffman, Padberg and Rinaldi, eight workstations connected in parallel solve problems from the test set documented -in the Crowder, Johnson and Padberg 1983 Operations Research article. Very inexpensive, networked workstations are now solving in minutes problems which were once considered not solvable in economically feasible times. In this peer-to-peer (as opposed to master-worker) implementation, interprocess communication was accomplished by using shared files and resource locks. Effective communication between processes was accomplished with a minimum of overhead (never more than 8% of total processing time). The implementation procedures and computational results will be presented.