Is there documentation for JFR events

[Erik Gahlin]

Hi Sean,

Different JVM versions have different events.

You can see event metadata by using the jfr tool located in the JAVA_HOME/bin directory.

$ jfr metadata recording.jfr

…

@Name("jdk.DataLoss")
@Category("Flight Recorder")
@Label("Data Loss")
@Description("Data could not be copied out from a buffer, typically because of contention")
class DataLoss extends jdk.jfr.Event {
  @Label("Start Time")
  @Timestamp("TICKS")
  long startTime;

  @Unsigned
  @DataAmount("BYTES")
  @Label("Amount")
  @Description("Amount lost data")
  long amount;

  @Unsigned
  @DataAmount("BYTES")
  @Label("Total")
  @Description("Total lost amount for thread")
  long total;
}

…

Erik

> On 29 Dec 2019, at 06:12, Sean Bridges <sean.bridges at gmail.com> wrote:
> 
> Hello,
> 
> Is there documentation for which JFR events are emitted by the JVM, what
> those events mean, and what fields those events have?
> 
> The closest I could find to a list of events was the profiling
> configuration,
> 
> https://github.com/AdoptOpenJDK/openjdk-jdk/blob/master/src/jdk.jfr/share/conf/jfr/profile.jfc
> 
> But I don't see any documentation for what data is in those events, or what
> those events mean.
> 
> For example, jdk.DataLoss looked like an interesting event, but googling
> for it doesn't reveal anything.
> 
> Thanks,
> 
> Sean