1. A non-transitory computer-readable storage medium storing therein a computer program that causes a computer to perform a procedure comprising: identifying resources which are respectively used upon execution of tasks included in a plurality of workflows, based on workflow definition information that defines content of each of the tasks included in the plurality of workflows; identifying, among the tasks included in the plurality of workflows, tasks that operate on a same exclusive resource, based on a result of the identifying of resources; determining an execution sequence of the identified tasks, based on the content of each of the identified tasks, the execution sequence including exclusive control on the exclusive resource to be operated by the identified tasks; identifying, among the identified tasks, one or more first tasks whose execution is omissible based on the content of each of the identified tasks and the execution sequence; and executing one or more second tasks and skipping execution of each of the one or more first tasks, the one or more second tasks being other than the one or more first tasks among the tasks included in the plurality of workflows.