RFR: 8307517: Add VMErrorCallback infrastructure to extend hs_err dumping

[David Holmes]

On Fri, 5 May 2023 16:42:22 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> src/hotspot/share/utilities/vmError.hpp line 232:
>> 
>>> 230: 
>>> 231: class VMErrorCallbackMark : public StackObj {
>>> 232:   Thread* _thread;
>> 
>> Why would we need the thread here? Why not use Thread::current in dtor? This object is only used as stack object, right?
>
> I was treading in Runtime code and Coleen usually wants to use cached-away Thread pointers instead of calling Thread::current() repeatedly. I'm fine with either solution.

Given the context it would have to be `Thread::current_or_null_safe()`. But yes we prefer not to re-materialize the current thread if we already have it at hand.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13824#discussion_r1187061050