RFR: 8296401: ConcurrentHashTable::bulk_delete might miss to delete some objects [v2]

[Axel Boldt-Christmas]

On Mon, 5 Dec 2022 10:17:18 GMT, Leo Korinth <lkorinth at openjdk.org> wrote:

>> ConcurrentHashTable::bulk_delete might miss to delete some objects if a bucket has more than 256 entries. Current uses of ConcurrentHashTable are not harmed by this behaviour. 
>> 
>> I modified gtest:ConcurrentHashTable to detect the problem (first commit), and fixed the problem in the code (second commit).
>> 
>> Tests passes tier1-3.
>
> Leo Korinth has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - growable stacked
>  - Revert "working!"
>    
>    This reverts commit 5366f22c7202eaa2182976c084d02e9af4f56de0.

src/hotspot/share/utilities/concurrentHashTable.inline.hpp line 524:

> 522:     }
> 523:     for (size_t node_it = 0; node_it < nd; node_it++) {
> 524:       Node* ndel = node_it < BULK_DELETE_LIMIT ? ndel_stack[node_it] : extra.at(node_it - BULK_DELETE_LIMIT);

Needs to be a reference (`Node*& ndel`) or `DEBUG_ONLY(ndel = (Node*)POISON_PTR;)` will be a no-op.

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PR: https://git.openjdk.org/jdk/pull/10983