URGENT RFR (S): fix for Test8004741.java crashes with SIGSEGV in JDK10-hs nightly (8185273)

Daniel D. Daugherty daniel.daugherty at oracle.com
Mon Jul 31 16:50:24 UTC 2017

On 7/31/17 10:46 AM, Roman Kennke wrote:
> Am 31.07.2017 um 17:14 schrieb Daniel D. Daugherty:
>> On 7/31/17 8:42 AM, Roman Kennke wrote:
>>> Hi Dan,
>>> You could also do_thread() on the VMThread, and let the ThreadClosurer
>>> filter it. I believe the ThreadClosure in safepoint.cpp (currently only
>>> consumer) already filters it. This would make it consistent with
>>> Threads::possibly_parallel_oops_do() (and infact, that latter method
>>> could just use the new Threads::parallel_java_threads_do() but this is
>>> beyond the scope). I leave that to you to decide though.
>> I'm good with just adding the missing part of the "claims" protocol.
>> I'm not comfortable with applying the closure to the VMThread since
>> I'm just visiting the GC sandbox as it were... :-)
> Ok. I'll do it in a followup then. IMO it would be best if there is
> *one* place that does the claiming protocol (i.e.
> parallel_java_threads_do() which should probably be renamed to
> parallel_threads_do() ), and have possibly_parallel_oops_do() use that
> via a private ThreadClosure. Best to do it asap, as long as there's only
> 1 user it's easy to see that it's correct ;-)

Thanks. I can file a follow up bug:

     cleanup parallel_java_threads_do() and possibly_parallel_oops_do()

and assign it to you if you like...

>>> I'd also include the fix for assert_all_threads_claimed() because it's
>>> related (and the cause for me not noticing this slip). But that is up to
>>> you too. ;-)
>> Yes, I plan to kick off another JPRT run with the additional fix for
>> assert_all_threads_claimed()... If that goes well, then I'll include
>> it...
> Great!

Done. And I sent out the diffs...

>> P.S.
>> Reminder: you're supposed to be on vacation! (But I do appreciate
>> you taking the time to chime in here...)
> Yeah, I should be at the Atlantic already, but my son got sick and we
> have to delay travel a little bit...

Hope your son gets well soon...

> And in reply to Aleksey: yes there will be more callers of
> Threads::parallel_java_threads_do() in the future :-) We've got one in
> Shenandoah already...
> Thanks for doing this!
> Cheers,
> Roman


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