RFR: 8290482: Update JNI Specification of DestroyJavaVM for better alignment with JLS, JVMS, and Java SE API Specifications [v4]

[Robbin Ehn]

On Tue, 20 Sep 2022 10:37:41 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> This update is primarily about changes to the JNI Invocation API specification, mainly in relation to `DestroyJavaVM`. The motivation for the changes is to align with changes being made to the JLS, JVMS and `java.lang.Runtime`, specifications in relation to VM termination - ref:
>> 
>> JDK-8290196 12.8: Clarify the definition of program exit
>> https://bugs.openjdk.org/browse/JDK-8290196
>> 
>> JDK-8290388 5.7: Clarify the definition of JVM termination
>> https://bugs.openjdk.org/browse/JDK-8290388
>> 
>> JDK-8290036 Define and specify Runtime shutdown sequence
>> https://bugs.openjdk.org/browse/JDK-8290036
>> 
>> Mostly these are just non-normative changes to the JNI spec prose but there are two actual specification changes:
>> 
>> 1.  The fact it is an error to detach a thread with active Java frames was only mentioned in the overview section, not in the actual `DetachCurrentThread` specification. (Just an oversight - the VM already checked this)
>> 
>> 2.  We need to make it an error to call `DestroyJavaVM` from an attached thread with active Java frames (as this can't work for the same reason we disallow `DetachCurrentThread`). This requires an implementation change in Hotspot.
>> 
>> Issue 2 covers the code change, and regression test, in this PR.
>> 
>> In addition the specification changes can be seen here:
>> 
>> - specdiff: http://cr.openjdk.java.net/~dholmes/8290482/8290482-jni-spec/diff.html
>> - original: http://cr.openjdk.java.net/~dholmes/8290482/8290482-jni-spec/jni-invocation-original.html
>> - new: http://cr.openjdk.java.net/~dholmes/8290482/8290482-jni-spec/jni-invocation-new.html
>> 
>> The specification itself is not open but comments on the spec changes are welcome - though please see the JBS issue and CSR request first. The revised wording has already been extensively reviewed/negotiated between Alex Buckley, Stuart Marks and myself, so any change must either be a glaring error/problem or else a trivial adjustment.
>> 
>> Thank you.
>
> David Holmes has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix JniVersion test

Looks good, thank you!

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Marked as reviewed by rehn (Reviewer).

PR: https://git.openjdk.org/jdk/pull/10352