RFR: 8365199: Use a set instead of a list as the intermediary Klass* storage to reduce typeset processing [v5]

Markus Grönlund mgronlun at openjdk.org
Wed Aug 13 14:31:01 UTC 2025


> Greetings,
> 
> This change set is a performance improvement to speed up JFR typeset processing.
> 
> It accomplishes this by using a set instead of a list as the intermediary Klass* storage.
> 
> Further, the existing JfrSet implementation (currently backed by a linked-list ResizeableResourceHashTable) is optimized to use instead a slimmed open-addressing implementation, premised on the invariant that our sets are key sets. 
> 
> Running the test program attached to the JIRA issue results in a 100% performance improvement in total running time (by reducing the work set of Klass: es being processed by the JFR Recorder Thread).
> 
> Testing: jdk_jfr, stress tests
> 
> Thanks
> Markus

Markus Grönlund has updated the pull request incrementally with one additional commit since the last revision:

  less than or equal to max_initial_size

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26733/files
  - new: https://git.openjdk.org/jdk/pull/26733/files/c1707f85..9b9db9f2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26733&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26733&range=03-04

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26733.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26733/head:pull/26733

PR: https://git.openjdk.org/jdk/pull/26733


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