JDK-8272977 : G1: Improve evacuation failure for regions with many objects
  • Type: Sub-task
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 18
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • Submitted: 2021-08-25
  • Updated: 2021-11-30
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Other
tbdUnresolved
Related Reports
Relates :  
JDK-8256265 - G1: Improve parallelism in regions that failed evacuation
Relates :  
JDK-8276094 - Region Pinning in G1
Relates :  
JDK-8254738 - G1: Improve generation placement heuristics for regions that could not be evacuated
Description
JDK-8254739 started storing the exact locations of objects that failed evacuation in lists; this is useful and faster than just iterating over the whole region object-by-object trying to find those that failed evacuation.

After a certain amount of failed objects in a region, this mechanism is more costly (in time and space) than just giving up and falling back to something else (like iterating over all objects).

This situation is supposed to be more frequent with pinned regions, so more urgent to investigate then.

Investigate implementing this or an alternative algorithm to do that.
Comments
Thanks Thomas for creating this.
26-08-2021