RFR: 8215451: JNI IsSameObject should not keep objects alive

[Per Liden]

On 12/17/18 12:15 PM, Kim Barrett wrote:
>> On Dec 17, 2018, at 3:08 AM, Per Liden <per.liden at oracle.com> wrote:
>> On 12/17/18 8:44 AM, David Holmes wrote:
>>> On 17/12/2018 2:59 pm, Kim Barrett wrote:
>>>> Responding to David - the resolve keeps the jweak's referent alive for
>>>> the current collection cycle. It could still die in some later
>>>> collection cycle, unless the described iteration happens again.
>>>> JDK-8188055 is the same problem for j.l.r.Reference.
>>> Okay - thanks. That seems undesirable. Unclear why this hasn't been an issue in the past.
>>
>> Generally speaking, this is not a problem for STW GCs. It's only a problem for concurrent marking GCs (like G1 and ZGC), but G1 is also doing STW young collections, which can hide the problem or make it harder to reproduce.
> 
> It's also not a problem for incremental update concurrent marking GCs
> (like CMS).  Instead, those have other problems.
> 

Agree.

/Per