1. An information processing apparatus which uses an operation system that is capable of giving a plurality of threads an execution opportunity sequentially by a thread switching and which makes a plurality of threads concurrently execute tasks stored in a task queue associated with the thread a prescribed number of times of execution, the information processing apparatus comprising: a plurality of processors that concurrently execute the plurality of threads without using the thread switching, each of the plurality of threads executing a process, the process including: generating a task from among a plurality of tasks into which a serial program processing corresponding to a processing request is divided; selecting a task queue associated with one of the plurality of threads; enqueuing the generated task to the selected task queue; tying tasks with a similar function from among the tasks which are enqueued by the task queue associated with the plurality of threads; dequeuing the enqueued task; executing a first task stored in one of the plurality of task queues sequentially after executing the dequeued task; executing a second task stored in the selected task queue sequentially after executing the dequeued task, when the dequeued task is not tied with any of the plurality of tasks; and tying the executed dequeued task with the first task, when the address of a function of the executed dequeued task corresponds to an address of the function of the first task.