RFR: 8281335: Allow a library already loaded via System::loadLibrary to be loaded as a raw library [v3]

[Mandy Chung]

On Tue, 15 Feb 2022 19:59:11 GMT, Mandy Chung <mchung at openjdk.org> wrote:

>> src/java.base/share/classes/jdk/internal/loader/NativeLibraries.java line 427:
>> 
>>> 425:             new ConcurrentHashMap<>();
>>> 426: 
>>> 427:     static void acquireNativeLibraryLock(String libraryName) {
>> 
>> Note sure about these two routines. Should they be shared? Should we have two locks, one for JNI, one for raw? Of course, as is the code looks fine - but I wonder if a single lock isn't overly strict.
>
> I initially planned to come back to this but I obviously forgot.  
> 
> This does not need the per-library locking for JNI library which avoids the deadlock due to the class and library loading scenarios involving JNI_OnLoad, class initialization, and `Sytem::loadLibrary`.   I now removed the locking entirely as it uses the concurrent hash map to register/unregister the loaded libraries.  Much simplified.

Thanks again for the feedback.  This version is much cleaner.

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PR: https://git.openjdk.java.net/jdk/pull/7435