JDK-8278917 : Use Prev Bitmap for recording evac failed objects
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 19
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2021-12-16
  • Updated: 2022-01-22
  • Resolved: 2021-12-21
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JDK 19
19 b03Fixed
Related Reports
Relates :  
JDK-8254739 - G1: Optimize evacuation failure for regions with few failed objects
Relates :  
JDK-8256265 - G1: Improve parallelism in regions that failed evacuation
Relates :  
JDK-8276094 - Region Pinning in G1
Description
Currently the evacuation failure handling is recording the failed objects during evacuation in a set backed by G1SegmentedArray. Later when processing the objects the set needs to be sorted to allow for efficient zapping of the areas between the live objects. During this phase we also mark the live objects in the prev mark bitmap to allow for correct verification. 

We can optimize away the sorting part mention above by directly mark failing objects in the mark bitmap and use the marks to know which objects needs processing.
Comments
Changeset: f4f2f32c Author: Stefan Johansson <sjohanss@openjdk.org> Date: 2021-12-21 14:03:08 +0000 URL: https://git.openjdk.java.net/jdk/commit/f4f2f32cd16158d8d4d2b552cd74531f25c45a29
21-12-2021
A pull request was submitted for review. URL: https://git.openjdk.java.net/jdk/pull/6867 Date: 2021-12-16 16:40:09 +0000
17-12-2021