JDK-8236594 : G1: Provide object pinning
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 15
  • Priority: P4
  • Status: Closed
  • Resolution: Duplicate
  • Submitted: 2019-12-30
  • Updated: 2024-02-23
  • Resolved: 2024-02-23
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tbdResolved
Related Reports
Duplicate :  
JDK-8318706 - Implement JEP 423: Region Pinning for G1
Duplicate :  
JDK-8269419 - G1: Support pinned Ojbect and remove/simplify GCLocker usage in G1
Relates :  
JDK-8254738 - G1: Improve generation placement heuristics for regions that could not be evacuated
Relates :  
JDK-8254167 - G1: Record regions where evacuation failed to provide targeted iteration
Relates :  
JDK-8253600 - G1: Fully support pinned regions for full gc
Relates :  
JDK-8192647 - GClocker induced GCs can starve threads requiring memory leading to OOME
Relates :  
JDK-8254739 - G1: Optimize evacuation failure for regions with few failed objects
Description
G1 presently uses the GCLocker mechanism to support JNI critical array and string operations.  It could instead use object pinning via region pinning.
Comments
Also we need some printing on how many pinned/evac failed regions per region type were.
14-10-2020
Given that we will likely reuse the existing evacuation failure mechanism for implementing this, change the evacuation failure handling to distinguish between real evacuation failures and pinning.
14-10-2020
Some code attempts to wait until the GCLocker is inactive, i.e. all code has left JNI critical sections to achieve maximum compaction during a VM operation. Examples are VM_GC_HeapInspection::collect and HeapShared::run_gc(). Some alternative should be found that is potentially more universal than the current code.
10-06-2020