RFR: 8327450: The result of jfr view active-settings is invalid if jfr file is created by JDK 11 or JDK 8

[Long Yang]

Hi all

Could I have a review of this patch ?

If the jfr file is created by JDK 8 or JDK 11, and use jfr view to show the active-settings view, the result is invalid, missing many settings.

jfr view active-settings j11.jfr

Active Settings

Event Type Enabled Threshold Stack Trace Period Cutoff Throttle
------------- ---------- ------------ -------------- --------- --------- -----------
File Force true 20 ms true


---------------------------------------------------------
jfr summary j11.jfr
...
 Event Type Count Size (bytes)
=============================================================
...
 jdk.ActiveSetting 292 9528
...

The reason is the endTime of jdk.ActiveSetting on JDK 8 or JDK 11 increases naturally, the time between two consecutive events is approximately a few microseconds, but the query statement of active-settings view used LAST_BATCH(), It assumes that the end time of events are the same. For JDK 17 and above, this assumption is correct, but not for JDK 8 and JDK 11.

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Commit messages:
 - 8327450: The result of jfr view active-settings is invalid if jfr file is created by JDK 11 or JDK 8

Changes: https://git.openjdk.org/jdk/pull/18137/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18137&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327450
  Stats: 42 lines in 7 files changed: 27 ins; 0 del; 15 mod
  Patch: https://git.openjdk.org/jdk/pull/18137.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18137/head:pull/18137

PR: https://git.openjdk.org/jdk/pull/18137