javajfr

-XX:StartFlightRecording start recording 1 and 2, why two recordings, what's the difference?

-XX:StartFlightRecording start recording 1 and 2, why two recordings, what's the difference?

By default is 250 MB, what if 250 MB is reached? Auto dump or cover old with new?

$jcmd 247628 JFR.check
247628:
Recording 1: name=1 maxsize=250.0MB (running)

Recording 2: name=2 maxsize=250.0MB (running)
Solution

  • -XX:StartFlightRecording only starts one recording, but if it's specified twice, two recordings begin. It's also possible to start another recording using jcmd.

    When 250 MB is reached, the oldest 10-15 MB are removed and filled with new data.