RFR: 8352414: JFR: JavaMonitorDeflateEvent crashes when deflated monitor object is dead

[Erik Gahlin]

On Thu, 20 Mar 2025 01:13:09 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Being a replacement for the `_sync_Deflations` counter it should probably count these null ones too.
>
> With regards to the event definition @egahlin suggests:
>> It might be worth mentioning it in the field description, e.g. "If null or N/A, the object has been garbage collected", but that is all. (Null is represented as 0 in the file format, which the parser will interpret as a missing value. Both 'jfr print' and JMC will display "N/A")

That is if null is used instead of dropping the event. I don't have an opinion on what is the best approach as it depends on how the event is being used.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24121#discussion_r2004597567