RFR: 8273695: Safepoint deadlock on VMOperation_lock

[Robbin Ehn]

On Tue, 21 Sep 2021 19:52:43 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Fixed.
>> 
>> No, we do not need to update it.
>> But maybe we want to, to avoid hitting poll-sites.
>> The reason not to do it is that it is preferable to have the plain query should_process() not having side-effects.
>> 
>> I need to think about that, thanks for bringing that up.
>
> Hmmm... good point about `should_process()` not having side effects.

This case could notice the update:
bool q1 = should_process(jt, true);
bool q_that_updates_poll_value = should_process(jt, false);
bool q2 = should_process(jt, true);

So q2 can be false while q1 is true. I do not think this is a problem, but worth considering the implications.

I think we should update the poll value even if I do not like it. (running some tests)

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PR: https://git.openjdk.java.net/jdk/pull/5613