RFR: 8282153 JFR: Check for recording waste

[Erik Gahlin]

Hi,

Could I have a review of test that looks for wasted space in recording files. Waste is typically constant pool data that is not referenced by an event. There have been issues with this in the past. 

I set an upper limit of 2% waste. It's typically around 0,7% in the test. Unused threads create waste and something we may want to prevent in the future. The fix relies on the method RecordingFile::write(Path, Predicate) being added. See "JDK-8271232: JFR: Scrub recording data"

The test prints a histogram of the event types to make sure expected events are emitted.

Testing: jdk/jdk/jfr/jvm/TestWaste.java 100 times

Thanks
Erik

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Commit messages:
 - Initial

Changes: https://git.openjdk.java.net/jdk/pull/7586/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7586&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8282153
  Stats: 125 lines in 1 file changed: 125 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7586.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7586/head:pull/7586

PR: https://git.openjdk.java.net/jdk/pull/7586