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  1. JDK
  2. JDK-4360113

Evict nmethods when code cache gets full

    Details

    • Type: Bug
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 1.3.0
    • Fix Version/s: hs17
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
    • Resolved In Build:
      b09
    • CPU:
      generic
    • OS:
      solaris_2.5.1

      Backports

        Description

        Presently the VM is started with a fixed limit on the size of
        generated code. When classes gets unloaded, the corresponding
        nmethods gets flushed from the code cache.

        If the code cache limit is reached, no more compilation occurs,
        even is class unloading occurs at a future point. For most
        programs this is a non-issue, but this failure has been observed
        for the Cloudscape big app, which compiles SQL->Java on the fly
        without ever unloading code.

        A reasonable solution would be to write the currect GC invocation
        count in an nmethod whenever it is seen on the stack (already done
        for non-reentrant methods). If the code cache fills up, we can
        force deoptimization and flushing of the nmethods with the lowest
        GC counts.

        steffen.grarup@eng 2000-08-07

        An improved version of the scheme above would be to force frequent
        safepoints when the code cache get close to the limit. At each
        safepoint we could write the current GC invocation count in all
        nmethods seen on stack. This would greate reduce the risk of
        flushing a hot non-allocating nmethod.
        steffen.grarup@eng 2000-10-16

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                • Assignee:
                  kvn Vladimir Kozlov
                  Reporter:
                  dstoutamsunw David Stoutamire (Inactive)
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