RFR: 8277930: Add unsafe allocation event to jfr [v5]

[Erik Gahlin]

On Tue, 30 Nov 2021 11:04:44 GMT, xpbob <duke at openjdk.java.net> wrote:

>> Unsafe is used in many Java frameworks.
>> When the framework has a unsafe memory leak , there is no way to know what code is causing it.
>> Add unsafe allocation event to jfr.
>> Records the size and stack allocated.
>> This event is off by default
>
> xpbob has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
> 
>  - Merge branch 'openjdk:master' into JDK-8277930
>  - remove whitespace
>  - add free and Reallocate event
>  - Merge branch 'openjdk:master' into JDK-8277930
>  - 8277930: Add unsafe allocation event to jfr

What about overhead (if JFR is disabled)? 

This looks like it could be a hot path for some applications.

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PR: https://git.openjdk.java.net/jdk/pull/6591