An information processing system (100,200) in which data is processed in a stream processing format, the information processing system comprising: a plurality of storage devices (102,201) comprising a first storage device, a second storage device, and a third storage device, wherein each of the storage devices is configured to output data to a first path connected to an arithmetic device out of a plurality of arithmetic devices; the plurality of arithmetic devices comprising a first arithmetic device, a second arithmetic device, a third arithmetic device, a fourth arithmetic device, and a fifth arithmetic device, wherein each of the arithmetic devices is configured to receive a message instructing a backup of an internal state at at least two first paths; output data to a second path connected to a storage device or another arithmetic device; in response to receiving the message at the at least two first paths, back up its internal state, and output another message instructing a backup of an internal state to the second path, and the first arithmetic device is slow in operation and the fifth arithmetic device is fast in operation; and a control device configured to acquire information of a waiting time until the second arithmetic device receives the message at the at least two first paths, wherein the waiting time is estimated based on the processing loads of the first arithmetic device and the third arithmetic device, determine whether or not the waiting time is equal to or more than a first threshold, based on the acquired information, and, when it is determined that the waiting time is equal to or more than the first threshold, change a first configuration, wherein the second arithmetic device is coupled to the first storage device through the first arithmetic device, and the second arithmetic device is coupled to the second storage device through the third arithmetic device, to a second configuration, wherein the second arithmetic device is coupled to the first storage device through the first arithmetic device, the fourth arithmetic device, the third storage device, and the fifth arithmetic device. a plurality of storage devices (102,201) comprising a first storage device, a second storage device, and a third storage device, wherein each of the storage devices is configured to output data to a first path connected to an arithmetic device out of a plurality of arithmetic devices; the plurality of arithmetic devices comprising a first arithmetic device, a second arithmetic device, a third arithmetic device, a fourth arithmetic device, and a fifth arithmetic device, wherein each of the arithmetic devices is configured to receive a message instructing a backup of an internal state at at least two first paths; output data to a second path connected to a storage device or another arithmetic device; in response to receiving the message at the at least two first paths, back up its internal state, and output another message instructing a backup of an internal state to the second path, and the first arithmetic device is slow in operation and the fifth arithmetic device is fast in operation; and a control device configured to acquire information of a waiting time until the second arithmetic device receives the message at the at least two first paths, wherein the waiting time is estimated based on the processing loads of the first arithmetic device and the third arithmetic device, determine whether or not the waiting time is equal to or more than a first threshold, based on the acquired information, and, when it is determined that the waiting time is equal to or more than the first threshold, change a first configuration, wherein the second arithmetic device is coupled to the first storage device through the first arithmetic device, and the second arithmetic device is coupled to the second storage device through the third arithmetic device, to a second configuration, wherein the second arithmetic device is coupled to the first storage device through the first arithmetic device, the fourth arithmetic device, the third storage device, and the fifth arithmetic device.