For a thread where data is to be popped off of queue storage, whether or not there is data that can be popped out of the queue storage accessed is first checked and then the data, if any, is popped. When there is no such data, the thread pushes thread information, including the identification information of its own thread, on the same queue and then releases a processor and shifts to a standby state. For a thread that is to push the data, when there is the thread information in the queue, it is determined that there is a thread waiting for the data, and then the data is sent after the thread information has been popped, which in turn resumes the processing.