17 Flight Recorder Configurations
Flight Recorder configurations control the amount of data that is recorded.
Flight Recorder uses two preconfigured configurations, default.jfc
and profile.jfc
. These configurations have predefined
settings for each event type. Both of these configurations are located in
<java_home>/lib/jfr
. By default, Flight
Recorder uses the default.jfc
configuration when you start
a recording. The default.jfc
configuration is recommended
for continuous recordings. It gives a good balance between data and
performance (typically, less than 1% overhead). The
profile.jfc
configuration records more events and
is useful while profiling an application.
In most cases, the preconfigured configurations are sufficient. However, there might
be a scenario while analyzing a recording that some events are disabled by
default. To enable these events, create a custom configuration. Use JDK
Mission Control to configure the event settings by using one of the existing
configurations. Make a copy of an existing configuration and then modify it.
Don't modify the default configurations. Specify which configuration to use
with the settings
command-line option when starting a
recording. For example:
-XX:StartFlightRecording:filename=recording.jfr,dumponexit=true,settings=default.jfc
-XX:StartFlightRecording:filename=recording.jfr,dumponexit=true,settings=mysettings.jfc