JDK-8307348 : Parallelize heap walk for ObjectCount(AfterGC) JFR event collection
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 11,17,20,21
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2023-05-03
  • Updated: 2023-07-06
  • Resolved: 2023-05-10
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JDK 17 JDK 21
17.0.9Fixed 21 b22Fixed
Related Reports
Blocks :  
JDK-8276696 - ParallelObjectIterator freed at the wrong time in VM_HeapDumper
Relates :  
JDK-8199712 - Flight Recorder
Relates :  
JDK-8215624 - Add parallel heap iteration for jmap –histo
Description
(Provisionally assigning this to myself, but Oli Gillespie [not an Author yet] would do the actual work)

ObjectCount(AfterGC) JFR event performs the single-threaded heap walk to count instances at GC pauses. After JDK-8215624, we can use the parallel heap walking facilities for this. Should be enough to just call `HeapInspection::populate_table` with the number of available GC workers.
Comments
Fix Request (17u) Improves the JFR performance by using parallel threads during GC safepoint. The backport is not clean due to the number of contextual differences. Requires JDK-8276696 as the pre-requisite. Testing passes. See JDK 17u PR for more details.
03-07-2023
A pull request was submitted for review. URL: https://git.openjdk.org/jdk17u-dev/pull/1441 Date: 2023-06-15 09:19:12 +0000
15-06-2023
Changeset: 540c706b Author: Oli Gillespie <ogillesp@amazon.com> Committer: Aleksey Shipilev <shade@openjdk.org> Date: 2023-05-10 08:54:18 +0000 URL: https://git.openjdk.org/jdk/commit/540c706bbcbb809ae1304aac4f2a16a5e83cb458
10-05-2023
A pull request was submitted for review. URL: https://git.openjdk.org/jdk/pull/13774 Date: 2023-05-03 11:10:31 +0000
03-05-2023