RFR: 8273026: Slow LoginContext.login() on multi threading application [v6]

[Larry-N]

On Thu, 28 Oct 2021 17:45:44 GMT, Larry-N <duke at openjdk.java.net> wrote:

>> This fix adds a cache of service provider classes to LoginContext (in particular, it's a cache of LoginModules classes). The approach helps to increase the performance of the LoginContext.login() method significantly, especially in a multi-threading environment. Service Loader is used for polling on Service Provider classes, without instantiating LoginModules object if Service Provider name doesn't match record in .config file. The set of service providers is cached for each Context Loader separately.
>> This code passed successfully tier1 and tier2 tests on mac os.
>
> Larry-N has updated the pull request incrementally with one additional commit since the last revision:
> 
>   A Corrected the Loader.java testcase

Thanks, I've added `@clean` as you propose.

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PR: https://git.openjdk.java.net/jdk/pull/5748