DISTRIBUTED STREAMING SYSTEM SUPPORTING REAL-TIME SLIDING WINDOWS

In various embodiments, a process for providing a distributed streaming system supporting real-time sliding windows includes receiving a stream of events at a plurality of distributed nodes and routing the events into topic groupings. The process includes using one or more events in at least one of the topic groupings to determine one or more metrics of events with at least one window and an event reservoir including by: tracking, in a volatile memory of the event reservoir, beginning and ending events within the at least one window; and tracking, in a persistent storage of the event reservoir, events associated with tasks assigned to a respective node. The process includes updating the one or more metrics based on one or more previous values of the one or more metrics as a new event is added or an existing event is expired from the at least one window.