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  1. JDK
  2. JDK-6490394

G1: Allow heap shrinking / memory unmapping after reclaiming regions during Remark

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    • gc
    • b18
    • generic
    • generic

    Description

      Right now G1 can only expand the heap outside of full GC, never shrink it.

      Given that G1 does incrementally compact the heap, it might be a good opportunity to do that whenever regions are actually made available again (GC cleanup, possibly at the end of the mixed gc cycle).

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        1. 20190807-jdk11backportRemarkResize-dacapoLarge100MTo4G-h2.html
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          is blocked by

          Enhancement - null JDK-8071913 Filter out entries to free/uncommitted regions during iteration

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Resolved
          relates to

          Bug - A problem which impairs or prevents the functions of the product. JDK-8238686 G1 may waste lots of space or fail to uncommit when observing MinHeapFreeRatio during sizing after full gc

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Bug - A problem which impairs or prevents the functions of the product. JDK-8213898 CDS dumping of springboot asserts in G1ArchiveAllocator::alloc_new_region

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          JEP - Java Enhancement Proposal JDK-8204089 JEP 346: Promptly Return Unused Committed Memory from G1

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Closed

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              tschatzl Thomas Schatzl
              tonyp Tony Printezis
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