RFR (7xS): 8071280, 8162928, 8177707, 8177044, 8178148, 8175554, 8178151: Remembered set update/scan improvements

Kim Barrett kim.barrett at oracle.com
Thu Apr 20 00:06:18 UTC 2017

> On Apr 11, 2017, at 7:30 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 8071280: Specialize HeapRegion::oops_on_card_seq_iterate_careful() for
> use during concurrent refinement and updating the rset
> CR: https://bugs.openjdk.java.net/browse/JDK-8071280
> Webrev: http://cr.openjdk.java.net/~tschatzl/8071280/webrev
> As the title indicates, this change allows specializations of
> HeapRegion::oops_on_card_seq_iterate_careful() according to current GC
> phase (concurrent or during gc) to allow to remove some checks.
> This is mostly a preparatory change for the next ones.

Only this changeset.  I’ll be sending out comments on others later, separate messages for each.

 149   assert(ClassUnloadingWithConcurrentMark,

Is this assertion really correct?  There is a similar assertion in
block_size, but it is protected by a call to block_is_obj.  I'm not
seeing similar protection for this one.  Maybe I'm missing someting?

 728   }

Close brace is now mis-indented.

 329   template <class Closure, bool is_gc_active>
 330   inline bool do_oops_on_card_in_humongous(MemRegion mr,


 682   template <class Closure, bool is_gc_active>
 683   inline bool oops_on_card_seq_iterate_careful(MemRegion mr, Closure* cl);

It would be better to have the is_gc_active template parameter first.
That would allow the Closure parameter to be deduced in calls, e.g.
instead of

    card_processed = r->oops_on_card_seq_iterate_careful<G1UpdateRSOrPushRefOopClosure, true>(dirty_region, &update_rs_oop_cl);

one would use

    card_processed = r->oops_on_card_seq_iterate_careful<true>(dirty_region, &update_rs_oop_cl);

with Closure being deduced from the type of the argument in the call.


More information about the hotspot-gc-dev mailing list