JDK-8026752 : Cancel MetaspaceGC request for a CMS concurrent collection after GC
  • Type: Bug
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: hs25
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2013-10-16
  • Updated: 2018-06-21
  • Resolved: 2016-06-11
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JDK 9
9 b126Fixed
Related Reports
Relates :  
JDK-8064702 - Remove the CMS foreground collector
Description
The MetaspaceGC flag _should_concurrent_collect is set to false after a CMS concurrent collection.
It should probably also be cleared after a foreground CMS collection and a stop-the-world full collection.
Comments
8064702 removed the option to do a foreground CMS collection (collection that did all the parts of a concurrent CMS collection but in a STW pause).
23-05-2016
For CMS 1) A concurrent collection is requested (setting of the _should_concurrent_collect flag) and then an expand_and_allocate() call is made to satisfy the allocation. 2) If the expand_and_allocate() fails a STW full GC is done and the allocation is retried. The _should_concurrent_collect flag is not cleared here. 3) If the STW full GC does not free up enough space for the allocation a last-ditch GC is done (the fixed added for 8025635). When a concurrent CMS collection is started, it can finish as a foreground GC. The _should_concurrent_collect flag should be cleared here as well as after a STW full GC. Consider whether that clearing can be put into the gc_epilogue() for ConcurrentMarkSweepGeneration.
16-10-2013