On Wed, 18 Sep 2024 03:04:50 GMT, Ioi Lam <[email protected]> wrote:
>> This is the 6th PR for [JEP 483: Ahead-of-Time Class Loading &
>> Linking](https://bugs.openjdk.org/browse/JDK-8315737).
>>
>> The implementation of java.lang.invoke uses SoftReferences so that unused
>> MethodHandles, LambdaForms, etc, can be garbage collected.
>>
>> However, if we want to store java.lang.invoke objects in the AOT cache
>> ([JDK-8293336](https://bugs.openjdk.org/browse/JDK-8293336), the final step
>> in JEP 493), it's difficult to cache these SoftReferences -- SoftReferences
>> in turn point to ReferenceQueues, etc, which have dependencies on the
>> current execution state (Threads, etc) which are difficult to cache.
>>
>> The proposal is to add a new flag: `MethodHandleStatics.NO_SOFT_CACHE`. When
>> this flag is true, we avoid using SoftReferences, and store a direct
>> reference to the target object instead.
>>
>> [JDK-8293336](https://bugs.openjdk.org/browse/JDK-8293336) stores only
>> java.lang.invoke objects that refer to classes loaded by the
>> boot/platform/app loaders. These classes are never unloaded, so it's not
>> necessary to point to them using SoftReferences.
>>
>> This RFE modifies only the LambdaFormEditor and MethodTypeForm classes, as
>> that's the minimal modification required by
>> [JDK-8293336](https://bugs.openjdk.org/browse/JDK-8293336).
>>
>> ---
>> See [here](https://bugs.openjdk.org/browse/JDK-8315737) for the sequence of
>> dependent RFEs for implementing JEP 483.
>
> Ioi Lam has updated the pull request with a new target base due to a merge or
> a rebase. The incremental webrev excludes the unrelated changes brought in by
> the merge/rebase. The pull request contains eight additional commits since
> the last revision:
>
> - @dholmes-ora review comments
> - Merge branch 'jep-483-step-05-8293337-archive-method-handle-intrinsics' of
> /jdk3/yam/open into
> jep-483-step-06-8311071-avoid-soft-refs-in-java-lang-invoke
> - Merge branch 'jep-483-step-05-8293337-archive-method-handle-intrinsics' of
> /jdk3/yam/open into
> jep-483-step-06-8311071-avoid-soft-refs-in-java-lang-invoke
> - Do not use system property to limit usage to only CDS static dumps
> - Merge branch 'jep-483-step-05-8293337-archive-method-handle-intrinsics' of
> /jdk3/yam/open into
> jep-483-step-06-8311071-avoid-soft-refs-in-java-lang-invoke
> - Merge branch 'jep-483-step-05-8293337-archive-method-handle-intrinsics' of
> /jdk3/yak/open into
> jep-483-step-06-8311071-avoid-soft-refs-in-java-lang-invoke
> - Merge branch 'jep-483-step-05-8293337-archive-method-handle-intrinsics' of
> /jdk3/yak/open into
> jep-483-step-06-8311071-avoid-soft-refs-in-java-lang-invoke
> - 8311071: Add an option to avoid using SoftReferences in
> java.lang.invoke.MethodHandle
How does archiving and resolution of the linked `MethodType` instances work? In
particular how does archiving fill up the `MethodType::internTable` to ensure
`MethodType` uniqueness?
src/java.base/share/classes/jdk/internal/misc/CDS.java line 80:
> 78:
> 79: /*
> 80: * Wwhen dumping the static archive, CDS is able to archive
> MethodHandles.
Suggestion:
* When dumping the static archive, CDS is able to archive MethodHandles.
-------------
PR Review: https://git.openjdk.org/jdk/pull/21049#pullrequestreview-2312480746
PR Review Comment: https://git.openjdk.org/jdk/pull/21049#discussion_r1764930471
