RFR: 8252104: parallel heap inspection for ShenandoahHeap [v3]

[Lin Zang]

On Fri, 18 Sep 2020 08:00:24 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Lin Zang has refreshed the contents of this pull request, and previous commits have been removed. The incremental views
>> will show differences compared to the previous content of the PR.
>
> src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp line 1341:
> 
>> 1339:
>> 1340:     // Reset bitmap
>> 1341:     _aux_bit_map.clear();
> 
> Wait a sec, we have just uncommitted the aux bitmap, so `clear()` is bound to crash?

No, here the aux_bit_map.clear() is called after commit_memory(), so clear() is safe to reset the bitmap.
the uncommit_memory() was moved to reclaim_aux_bitmap_for_iteration() at line 1354

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PR: https://git.openjdk.java.net/jdk/pull/67