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  1. JDK
  2. JDK-6948537

CMS: BOT walkers observe out-of-thin-air zeros on sun4v sparc/CMT

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P2
    • Resolution: Fixed
    • Affects Version/s: hs17, 6u19
    • Fix Version/s: hs19
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
      gc
    • Introduced In Build:
      1.4.2
    • Introduced In Version:
    • Resolved In Build:
      b01
    • CPU:
      sparc
    • OS:
      solaris, solaris_10
    • Verification:
      Verified

      Backports

        Description

        BOT bulk-updates use memset(). However on Niagara memset() uses BIS
        for speed and this exposes concurrent readers to out-of-thin-air zeroes,
        which are fatal for concurrent BOT walks. Such concurrent reads of
        BOT entries subject to concurrent update are possible with non-contiguous
        spaces such as CMS (but not any other current GC in HotSpot).

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                • Assignee:
                  ysr Y. Ramakrishna
                  Reporter:
                  ysr Y. Ramakrishna
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                  Dates

                  • Created:
                    Updated:
                    Resolved:
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