RFR: 8315559: Delay TempSymbol cleanup to avoid symbol table churn [v10]

[Oli Gillespie]

On Mon, 13 Nov 2023 01:35:42 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Oli Gillespie has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix indentation, rename test helper
>
> test/hotspot/gtest/classfile/test_placeholders.cpp line 45:
> 
>> 43:   Symbol* D = SymbolTable::new_symbol("def2_8_2023_class");
>> 44:   Symbol* super = SymbolTable::new_symbol("super2_8_2023_supername");
>> 45:   Symbol* interf = SymbolTable::new_symbol("interface2_8_2023_supername");
> 
> This doesn't seem like the right way to update this test.  Doesn't this leave the symbols dangling?
> And in the face of potential queue draining, it seems to me this could lead the test to intermittent failures.

Updated to use the same 'create then drain' approach as the other test.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16398#discussion_r1406553070