RFR: 8264735: Make dynamic dump repeatable [v2]

[Yumin Qi]

On Tue, 6 Jul 2021 21:48:52 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Yumin Qi has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix comments, added check holding for DumpTimeTable_lock
>
> src/hotspot/share/cds/filemap.cpp line 497:
> 
>> 495:   // if (_saved_shared_path_table.size() > 0) {
>> 496:   //   MetadataFactory::free_array<u8>(loader_data, _saved_shared_path_table->_table);
>> 497:   // }
> 
> In `FileMapInfo::copy_shared_path_table()`:
> 
> 
>   Array<u8>* array = MetadataFactory::new_array<u8>(loader_data, (int)bytes, CHECK);
>   _saved_shared_path_table = SharedPathTable(array, _shared_path_table.size());
> 
> 
> You can remember the `array` pointer, e.g.
> 
> 
>   _saved_shared_path_table_array = array;
> 
> 
> 
> and then call `MetadataFactory::free_array<u8>(_saved_shared_path_table_array)` in this function.

Thanks. Remembering for later deletion is OK.

> src/hotspot/share/cds/lambdaProxyClassDictionary.hpp line 167:
> 
>> 165:   // We could not use default ctor, it will destroy allocation_type in debug version and fail to delete.
>> 166:   // see bug 8269537
>> 167:   DumpTimeLambdaProxyClassDictionary() : _count(0)  {}
> 
> Since you changed the construction call from 
> 
> (ResourceObj::C_HEAP, mtClass)DumpTimeLambdaProxyClassDictionary();
> 
> to
> 
> (ResourceObj::C_HEAP, mtClass)DumpTimeLambdaProxyClassDictionary;
> 
> 
> I think it's no longer necessary to add the `RunTimeLambdaProxyClassInfo()` and `DumpTimeSharedClassTable()` constructors in this PR. In 8269537, we should find a generic way to prevent this bug from happening.

Initialization of _count is still needed. I could remove DumpTimeSharedClassTable, but still, we should keep the ctor which initialize the two data members --- though they will be reset in update_counts. I will remove the comments.

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PR: https://git.openjdk.java.net/jdk/pull/4646