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  1. JDK
  2. JDK-8221632

Several corrections to java FlightRecorderOptions section

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    • Subcomponent:
      jfr
    • Resolved In Build:
      b29

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        Description

        https://docs.oracle.com/en/java/javase/12/tools/java.html
        Section: -XX:FlightRecorderOptions

        1)
        "Note:
        The -XX:+FlightRecorder option is no longer required to use JFR. This was a change made in JDK 8u40."
        CORRECTION: AFAIK JVM dropped the requirement for -XX:+FlightRecorder when JFR was open sourced, which is JDK 11 (NOT in JDK8u40).

        2)
        java -XX:FlightRecorderOptions=allow_threadbuffers_to_disk=true -version
        CORRECTION: Remove this parameter
        Using this parameter results in the following error (JDK 12+33 2019-03-19):
            [0.079s][error][arguments] -XX:FlightRecorderOptions=disk=... has been removed. Use -XX:StartFlightRecording=disk=... instead.


        3) threadbuffersize=size
            Please mention that the minimum size required is 4096

        4) When Flight Recorder was open sourced with JDK 11 the syntax for the command line option -XX:StartFlightRecording was extended.
        Previously the syntax was:

         -XX:StartFlightRecording=parameter=value.

        From JDK 11, the following syntax is also allowed.

        -XX:StartFlightRecording:parameter=value

        similar to unified logging (-Xlog:). It may make sense to call out that there are two ways, as there may be users with older releases and/or scripts that want to use the previous syntax.

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                • Assignee:
                  dholmes David Holmes
                  Reporter:
                  mseledtsov Mikhailo Seledtsov
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