Stream Data Processing Failure Recovery Method and Device

In a duplex configuration of stream data processing, all window operations can be used without stopping the process when adding a standby system. The time when the standby system server is added is stored as the reproduction time, and data copied from the data generated at or after the reproduction time is transmitted to the standby system. While the data processing in the in-use system is continued, changes in the execution state which occur in operators holding execution state at or after the reproduction time are recorded. The execution states are copied to the standby system for each operator in parallel with the data processing. At this time, the execution states of the operators at the reproduction time are reproduced from the execution states of the operators when the copy is performed and the record of the changes of the execution states, and the reproduced execution states are copied. When the execution states of all the operators have been copied, the standby system starts processing of the copied data which are generated at or after the reproduction time.