JDK-8223295 : ObjectMonitor: fields are closer than a cache line which permits false sharing
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: openjdk8u222
  • Priority: P4
  • Status: Resolved
  • Resolution: Won't Fix
  • Submitted: 2019-05-03
  • Updated: 2022-10-13
  • Resolved: 2022-10-13
Related Reports
Relates :  
JDK-8049737 - Contended Locking reorder and cache line bucket
Description
 ~/trunks/jdk8u-dev $ build/linux-x86_64-normal-server-fastdebug/images/j2sdk-image/bin/java -XX:+ExecuteInternalVMTests
...
Running test: ObjectMonitor::sanity_checks()
WARNING: the _header and _owner fields are closer than a cache line which permits false sharing.
WARNING: ObjectMonitor size is not a multiple of a cache line which permits false sharing.

Maybe we can partially backport JDK-8049737 to alleviate this.
Comments
After some consideration, I think there is no point in doing this partially in 8u at this time. Users can upgrade to later JDKs to get the fixes.
13-10-2022