RFR: 8282153 JFR: Check for recording waste [v2]

[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

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

  Make test more stable

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7586/files
  - new: https://git.openjdk.java.net/jdk/pull/7586/files/0a9b651f..8a7fd561

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7586&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7586&range=00-01

  Stats: 5 lines in 1 file changed: 3 ins; 0 del; 2 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