To update a data file being used by an execution program, while synchronizing processing contents among a plurality of processors constituting an FTC.

This computer system provided with a plurality of processors for executing multiple parallel processing acquires logical timing, which is defined by a specified step in the processing by the program being executed, to update data used in the program, monitors whether the processing of the program being executed reaches the acquired logical timing or not, and updates the data, without stopping the program being executed, when the processing of the program reaches the acquired logical timing.