RFR: JDK-8220671: Initialization race for non-JavaThread PtrQueues

[Kim Barrett]

> On Mar 25, 2019, at 9:26 AM, Roman Kennke <rkennke at redhat.com> wrote:
> 
> This thread went a bit off. May I propose this for review:
> 
> http://cr.openjdk.java.net/~rkennke/JDK-8220671/webrev.07/
> 
> it passes tier1 tests locally, and I submitted it to jdk/submit but that seems to have other hiccups.
> 
> WDYT?

I'm still not convinced the activation predicates for the STS joiners
are correct here.  And I'm not what the right predicate might be or if
it even exists.

Also, STS is presently a "GC" thing, and this would insinuate it into
non-GC code, and affect non-GC threads (such as the WatcherThread and
the JfrThreadSampler).

I still prefer using the NonJavaThreadsList_lock in NJT::pre/post_run
and around the the relevant state changes, such as setting the SATB
qset's _all_active member.