RFR: 8259242: Remove ProtectionDomainSet_lock [v2]

[Coleen Phillimore]

On Wed, 7 Apr 2021 12:39:19 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This change makes the DictionaryEntry pd_set reads lock free, because when I set a low SafepointTimeout on the findDeadlock test, these threads were waiting on the ProtectionDomainSet_lock.  This lock is a singleton that's taken for every dictionary entry.
>> 
>> I don't know if this change will make the test never timeout again, because removing this lock caused us to hit a low SafepointTimeout on another _no_safepoint_check lock that is not so easy to eradictate.
>> 
>> Tested with tiers 1-3.  There's a test that exercises this code in runtime/Dictionary/ProtectionDomainCacheTest.java.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add acquire/release and update names.

Thank you for reviewing, Patricio.

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PR: https://git.openjdk.java.net/jdk/pull/3362