RFR: 8215451: JNI IsSameObject should not keep objects alive

[Kim Barrett]

> 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.