8242593: JFR: EventFactory does not scale well past unique 1000 event

[Jaroslav Bachorík]

Hi Erik,

The patch looks good! I wonder, is there a test already for the
Summary.java which asserts it can properly handle the missing
metadata?

Cheers,

-JB-

On Sat, Jun 20, 2020 at 6:06 PM Erik Gahlin <erik.gahlin at oracle.com> wrote:
>
> Hi,
>
> Could I have review of a fix that prevents metadata to be written to
> native every time a new event is registered.
>
> This means there is small chance that the JVM will not be able to write
> the most recent metadata if a crash occurs and an emergency recording is
> created. This will not impact ordinary recordings or event streaming,
> since stale metadata is written out before a segment or chunk is complete
>
> For more details, see:
>
> https://mail.openjdk.java.net/pipermail/jmc-dev/2020-June/002279.html
>
> If the parser finds an event that lacks metadata, it will just skip that
> event. This will only occur if the JVM crashes within 1 second after new
> Java event is registered.
>
> I did a small experiment and the time it takes to register 50 events now
> drops from 350 ms to 50 ms.
>
> I also updated the 'jfr summary command', so it prints the event id if
> the metadata is missing. This makes it possible to verify that an event
> missing due to lack of metadata and not a configuration issue etc.
>
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8242593
>
> Webrev:
> http://cr.openjdk.java.net/~egahlin/8242593/
>
> Testing: jdk/jdk/jfr
>
> Thanks
> Erik
>
>