RFR: 8315559: Delay TempSymbol cleanup to avoid symbol table churn [v4]

[Coleen Phillimore]

On Tue, 31 Oct 2023 18:11:09 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Oli Gillespie has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Adress comments
>>   
>>   Fix indentation
>>   Improve tests
>>   Improve comment
>>   Remove redundant null check
>>   Improve naming
>>   Pop when >, not >= max len
>
> src/hotspot/share/oops/symbolHandle.hpp line 122:
> 
>> 120:     // If the queue is now full, implement a one-in, one-out policy.
>> 121:     if (Atomic::add(&_cleanup_delay_len, 1, memory_order_relaxed) > _cleanup_delay_max_entries) {
>> 122:       TempSymbolDelayQueueNode* result = _cleanup_delay.pop();
> 
> NonblockingQueue's push and pop operations are subject to ABA problems, and
> require the client to address that in some fashion. There's nothing here to do
> that. I think one possibility would be to wrap the push/pop calls in a
> GlobalCounter::CriticalSection and do a GlobalCounter::write_synchronize
> before deleting a node.

If you have to add more code to wrap NonblockingQueue, please implement it in a .cpp file.  I thought NBQ was sufficient for this.  Maybe we want some other data structure for this.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16398#discussion_r1378042617