The summarizer keeps its SummaryItem list until it is time to flush it to its dataListeners. The summarizer flushes on the earlier of:

Both the scheduled time and the dataItemThreshold are configurable properties of the summarizer. By using these properties to control the flush interval, you can balance the performance of the summarizer and the amount of summarized data that would be lost in a system crash.

When the summarizer flushes its data, it sends SummaryItems to the data listeners specified by the summarizer’s dataListeners property. These data listeners can be queues, and are usually one of the loggers that come with the data collection package. The summarizer’s dataListeners consists of a list of summary loggers, FormattingSummaryLogger or JTSQLTableSummaryLogger.