RFR: 8313332: Simplify lazy jmethodID cache in InstanceKlass

[Coleen Phillimore]

On Fri, 29 Mar 2024 15:25:48 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> This change simplifies the code that grows the jmethodID cache in InstanceKlass.  Instead of lazily, when there's a rare request for a jmethodID for an obsolete method, the jmethodID cache is grown during the RedefineClasses safepoint.  The InstanceKlass's jmethodID cache is lazily allocated when there's a jmethodID allocated, so not every InstanceKlass has a cache, but the growth now only happens in a safepoint.  This code will become racy with the potential change for deallocating jmethodIDs.
> 
> Tested with tier1-4, vmTestbase/nsk/jvmti java/lang/instrument tests (in case they're not in tier1-4).

Thank you Alex!

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PR Comment: https://git.openjdk.org/jdk/pull/18549#issuecomment-2031887624