RFR: 8282420: JFR: Remove event handlers [v3]

[Erik Gahlin]

> Hi,
> 
> Could I have a review of a fix that removes event handler classes for JFR. Bytecode for event instrumentation is now only added to the event class. Benefits are:
> 
> - No class memory leak in the boot class loader.
> - Reduce overhead from class loading during startup, which is important with additional JDK events that are coming (VirtualThreadStart etc.)
> - One less frame to traverse when recording a Java stack trace.
> 
> Future benefits are:
> 
> - Simplify creating instrumentation as a build step. See https://bugs.openjdk.java.net/browse/JDK-8279354
> - Simplify implementation of Event Metrics. See https://bugs.openjdk.java.net/browse/JDK-8224749
> 
> When the Security Manager is removed, much of the code being added for security reasons can be deleted.
> 
> There are few JFR hooks when code is being linked. Plan is to also use these for other events later. 
> 
> Testing: tier 1-4, jdk/jdk/jfr
> 
> Thanks
> Erik

Erik Gahlin has updated the pull request incrementally with one additional commit since the last revision:

  Typos in cleanups

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8383/files
  - new: https://git.openjdk.java.net/jdk/pull/8383/files/3e4d9068..81989dd6

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8383&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8383&range=01-02

  Stats: 3 lines in 2 files changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8383.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8383/head:pull/8383

PR: https://git.openjdk.java.net/jdk/pull/8383