RFR: 8242440: use separate, destroyable JavaVM instances per libgraal compiler thread [v2]

[Doug Simon]

On Sun, 17 Apr 2022 04:14:30 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Doug Simon has updated the pull request incrementally with six additional commits since the last revision:
>> 
>>  - avoid use of jobject for oop handles implementing foreign object references in libjvmci heap to HotSpot heap objects
>>  - inlined JVMCIRuntime::_jobjects
>>  - replace NULL with nullptr
>>  - added JVMCIRuntime_lock global
>>  - replace enum with const definition
>>  - rename thread parameter to current
>
> src/hotspot/share/jvmci/jvmciRuntime.hpp line 168:
> 
>> 166:   // destroying remaining JNI handles when the JavaVM associated
>> 167:   // with this runtime is shutdown.
>> 168:   GrowableArray<jobject>* _jobjects;
> 
> I think _jobjects should be a nested object rather than a pointer.

Fixed: https://github.com/openjdk/jdk/pull/8262/commits/1d5b815d0dbc4781059ec1b9e7375dc593af9438

> src/hotspot/share/jvmci/jvmciRuntime.hpp line 177:
> 
>> 175:   int _num_attached_threads;
>> 176:   enum {
>> 177:     cannot_be_attached = -1 // See _num_attached_threads
> 
> We no longer use enums (with unspecified type) to define constants.  Use `static const` instead.  (There's lots of old code that still does this, but new code should not.)

Fixed: https://github.com/openjdk/jdk/pull/8262/commits/53edb1d00a7d8ff6b22b3d9a32b7dc915874c3e7

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PR: https://git.openjdk.java.net/jdk/pull/8262