RFR: 8352075: Perf regression accessing fields [v21]
Coleen Phillimore
coleenp at openjdk.org
Thu Jun 5 22:16:54 UTC 2025
On Thu, 5 Jun 2025 05:17:48 GMT, Ioi Lam <iklam at openjdk.org> wrote:
>> Radim Vansa has updated the pull request incrementally with three additional commits since the last revision:
>>
>> - Moved jtreg test
>> - Improved documentation
>> - Fix coding style (asterisk placement)
>
> I have written a POC that shows that the table must be sorted again when dumping a dynamic CDS archive. See https://github.com/iklam/jdk/commit/dcd53ebaeab7b38be02aa5b896ce9e449a45418f
>
> Explanations are in [here](https://github.com/iklam/jdk/commit/dcd53ebaeab7b38be02aa5b896ce9e449a45418f#diff-fd7608607ecf305bb3535b500bff5d53ec216d2da25e3bad1a1d699f56b09283R199)
>
> I will create an RFE for the JDK mainline that adds built-in debugging support for the `(oldSym > newSym_orig)` condition as describe in the POC. Please wait for that before integrating this PR. I can help you write the code for re-sorting the tables.
As @iklam was saying in above, the table won't work for dynamic dumping for CDS and fails all these tests.
Array<u1>* FieldInfoStream::create_search_table(ConstantPool* cp, const Array<u1>* fis, ClassLoaderData* loader_data, TRAPS) {
+ if (CDSConfig::is_dumping_dynamic_archive()) {
+ // We cannot call validate_search_table. The _fieldinfo_search_table should be sorted by "requested" addresses,
+ // but validate_search_table will be getting Symbol* addresses from _constants, which has "buffered" addresses.
+ //
+ // For background, see new comments inside allocate_node_impl in symbolTable.cpp
+ return nullptr;
+ }
+
This fixes these tests.
-------------
PR Comment: https://git.openjdk.org/jdk/pull/24847#issuecomment-2946527410
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