RFR: 8252794: Creation of JNIMethodBlock should be done with a leaf lock [v2]

[Robbin Ehn]

On Wed, 9 Sep 2020 01:15:26 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Corrected comment
>
> src/hotspot/share/oops/method.cpp line 2190:
> 
>> 2188:     // Also have to add the method to the list safely, which the cld lock
>> 2189:     // protects as well.
>> 2190:     MutexLocker ml(JmethodIdCreation_lock,  Mutex::_no_safepoint_check_flag);
> 
> The comment above this states:
>  // Also have to add the method to the list safely, which the cld lock
>  // protects as well.
> I don't know what list is being referred to here but either the comment is incorrect or else the change of lock is
> incorrect!

We create the list with:
`cld->set_jmethod_ids(new JNIMethodBlock(capacity));`
And add to the list:
`return (jmethodID)cld->jmethod_ids()->add_method(m);`

I removed 'cld' from comment.

> src/hotspot/share/oops/method.cpp line 2214:
> 
>> 2212:     // Also have to add the method to the list safely, which the cld lock
>> 2213:     // protects as well.
>> 2214:     MutexLocker ml(JmethodIdCreation_lock,  Mutex::_no_safepoint_check_flag);
> 
> Ditto

Ditto fix

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PR: https://git.openjdk.java.net/jdk/pull/53