RFR: 8244661: JFR: Remove use of thread-locals for java.base events

[Erik Gahlin]

Hi,

Could I have a review of change that removes object caching for performance sensitive events in java.base. Instead events are written directly using the event handler. Purpose is to avoid memory bloat when using thread-locals together with virtual threads for project Loom, but it will benefit ordinary threads as well, so plan is to check it in for JDK 15.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8244661

Webrev:
http://cr.openjdk.java.net/~egahlin/8244661/

Testing: jdk/jdk/jfr + reproducer in the original allocation bug
https://bugs.openjdk.java.net/browse/JDK-8187234

Thanks
Erik