RFR: 8152113: Remove _last_ditch_collection GC-cause and avoid expanding heap on Metaspace OOM (original) (raw)

Stefan Johansson stefan.johansson at oracle.com
Thu Mar 17 17:03:02 UTC 2016


Hi,

Please review this change for RFE: https://bugs.openjdk.java.net/browse/JDK-8152113

Webrev: http://cr.openjdk.java.net/~sjohanss/8152113/hotspot.00/

Summary: Prior to this patch the GC-cause _last_ditch_collection has been used for 2 types of full-collections that clears soft references:

  1. Last resort when out of metaspace memory
  2. WhiteBox initiated full GC

These have not much in common and the GC-cause is strangely named when looking at its meaning. This cause also comes with an unwanted side-effect, it will expand the heap if possible and this is strange since it is not caused by a failed heap-allocation. This change removes the _last_ditch_collection cause and now we instead use two separate causes, _wb_full_gc for the WhiteBox-case and _metadata_GC_clear_soft_refs for the out of metaspace case. The idea is that these will work similar to _last_ditch_collection in every way except when it comes to growing the heap.

Testing: Run several tonga test-lists in RBT with G1, CMS and Parallel without seeing any new issues.

Thanks, Stefan



More information about the hotspot-gc-dev mailing list