RFR (M): 8201491: G1 support for java.lang.ref.Reference precleaning

[Kim Barrett]

> On May 7, 2018, at 6:49 PM, Kim Barrett <kim.barrett at oracle.com> wrote:
> 
>> On Apr 26, 2018, at 5:36 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
>> 
>> Hi all,
>> 
>> can I have reviews for this change that implements reference
>> precleaning like CMS for G1?
>> 
>> […]
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8201491
>> Webrev:
>> http://cr.openjdk.java.net/~tschatzl/8201491/webrev/
>> Testing:
>> hs-tier1-5, *many* times Kitchensink reference stress test
>> 
>> Thanks,
>> Thomas
> 
> Looks good.

I forgot a couple of things.  I don’t need a new webrev for these.

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src/hotspot/share/gc/shared/referenceProcessor.hpp
 291   // Returns whether the operation should be aborted.
 292   void preclean_discovered_references(BoolObjectClosure* is_alive,

Comment is wrong.  It's preclean_discovered_reflist that returns the
abort flag.

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src/hotspot/share/gc/g1/g1ConcurrentMarkThread.cpp
 313           if (G1UseReferencePrecleaning) {
 314             {

The second level of brackets here isn't needed.

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