A system includes a plurality of computers configured to process a computer program in parallel by executing a plurality of processes, respectively, in parallel, each process of the plurality of processes including at least one thread, and each of the plurality of computers including a first memory and a first processor coupled to the first memory and configured to execute the plurality of processes, respectively, and a management device configured to control the plurality of computers, the control device including a second memory, and a second processor coupled to the second memory, and based on parallelization rate, memory busy rate, operation number difference and processing time difference, execute an adjusting of a number of the threads included in at least one process of the plurality of processes.