JDK-8298597 : HdrSeq: support for a merge() method
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2022-12-12
  • Updated: 2025-05-12
  • Resolved: 2022-12-19
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Related Reports
Cloners :  
JDK-8305767 - HdrSeq: support for a merge() method
Relates :  
JDK-8298902 - AbsSeq::merge() should not dodge decaying stats
Relates :  
JDK-8339094 - Shenandoah: Fix up test output from ShenandoahNumberSeqTest
Relates :  
JDK-8297796 - GenShen: instrument the remembered set scan
Description
For GenShen's RS scan instrumentation, we want support for a merge() method for HdrSeq:s.

The rough shape of the spec for the proposed merge() method in HdrSeq class is:

// Merge the data in this HdrSeq into the HdrSeq, seq2, in the argument
// to the method, optionally clearing the data in this HdrSeq.
void merge(HdrSeq* seq2);

This will likely necessitate having the same or similar methods in
superclass hierarchy.

A PR will be opened once the changes have been implemented, refined,
tested and ready to initial discussion. Opening this issue in anticipation.
Comments
A pull request was submitted for review. URL: https://git.openjdk.org/shenandoah/pull/184 Date: 2022-12-15 19:33:36 +0000
16-12-2022
Splitting off the handling of decaying statistics into a separate ticket, deferring that work for now.
16-12-2022
The issue of updating the decaying statistics via a merge method requires careful thought. As it stands today, decaying statistics are not invoked or used in the case of HdrSeq:s subject to merge in the near-future. This space will be updated with a suitable design and possible API adjustments when we have a proposal ready.
14-12-2022