RFR: 8212879: Make JVMTI TagMap table not hash on oop address

[Daniel D. Daugherty]

On 11/2/20 8:22 AM, Coleen Phillimore wrote:
> On Mon, 2 Nov 2020 08:34:17 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:
>
>>> src/hotspot/share/prims/jvmtiTagMap.cpp line 126:
>>>
>>>> 124:   // concurrent GCs. So fix it here once we have a lock or are
>>>> 125:   // at a safepoint.
>>>> 126:   // SetTag and GetTag should not post events!
>>> I think it would be good to explain why. Otherwise, this just leaves the readers wondering why this is the case.
>> Maybe even move this comment to the set_tag/get_tag code.
> I was trying to explain why there's a boolean there but I can put this comment at both get_tag and set_tag.
>
>    // Check if we have to processing for concurrent GCs.

Typo: s/we have to processing/we have to do processing/


>    // GetTag should not post events because the JavaThread has to
>    // transition to native for the callback and this cannot stop for
>    // safepoints with the hashmap lock held.
>    check_hashmap(false);
>
> -------------
>
> PR: https://git.openjdk.java.net/jdk/pull/967