Event stream processing method and event stream processing program

A non-transitory computer readable storage medium that stores therein an event stream processing program causing a computer to execute an event stream processing comprising:

• wherein the event stream processing system including processing threads provided in each of a plurality of stages, the processing threads including a distribution control thread provided in a first stage, a first event processing thread and a second event processing thread provided in a second stage to execute, in response to a processing message, processing corresponding to the processing message, and a standard thread that is able to be a copy of either the first event processing thread or the second event processing thread,
• transmitting, by the distribution control thread, the processing message to either the first event processing thread or the second event processing thread,
• transmitting, by the distribution control thread, when an event processing thread of either the first event processing thread or the second event processing thread is in a heavy load state, a copy request message that requests converting the standard thread to the copy to a heavy-load event processing thread and registers the standard thread in a distribution destination list,
• transmitting, by the heavy-load event processing thread, parameters for operating as a copy of the heavy-load event processing thread to the standard thread in response to reception of the copy request message, and
• executing, by a copy standard thread that has received the parameters and being converted to the copy, processing corresponding to the processing message received from the distribution control thread by using the received parameters.