Flight Recorder Events

The Flight Recorder collects data about events; that is, occurrences in an application during runtime. An event can be described as a distinct data point with associated data; for example, the CPU load at a certain time.

This topic describes these features:

Event Characteristics
Event Types

Event Characteristics

Events have these characteristics:

Events can have thresholds; that is, you can configure the Flight Recorder to record an event only if it lasts longer than a specified time.
Events can have stack traces, which give user the ability to easily find the bottleneck.
Events can be periodically reported; for example, you can configure the Flight Recorder to report CPU load (the event) every second.

Event Types

The Flight Recorder collects information about three types of events:

Duration event; A duration event is something that happens during a period of time. duration events are logged when completed. The user can put a threshold on the Duration Events, so only events with duration greater than X is recorded. This is not possible for the other events.
Instant event; An instant event is instantaneous and will be logged each time one occurs.
Sample event; A sample event is one that is recorded at a regular interval to provide a sample of system activity; for example, the CPU load. Users can use the JFR to configure how often sampling occurs.