Parallel synchronous and asynchronous coupled simulated annealing

We propose a parallel synchronous and asynchronous implementation of the coupled simulated annealing (CSA) algorithm in a shared-memory architecture. The original CSA was implemented synchronously in a distributed-memory architecture. It synchronizes at each temperature update, which leads to idling and loss of efficiency when increasing the number of processors. The proposed synchronous CSA (SCSA) is implemented as the original, but in a shared-memory architecture. The proposed asynchronous CSA (ACSA) does not synchronize, allowing a larger parallel efficiency for larger numbers of processors. Results from extensive experiments show that the proposed ACSA presents much better quality of solution when compared to the serial and to the SCSA. The experiments also show that the performance of the proposed ACSA is better than the SCSA for less computationally intensive problems or when a larger number of processing cores are available. Moreover, the parallel efficiency of the ACSA improves by increasing the size of the problem. With the advent of the Multi-core Era, the use of the proposed algorithm becomes more attractive than the original synchronous CSA.