8257701: Shenandoah: objArrayKlass metadata is not marked with chunked arrays

[zhengyu123]

Usually, marking code calls Klass::oop_oop_iterate(), where it marks object klass metadata.

Shenandoah introduced chunked array processing a while ago to breakup marking a large array into chunks, then call oop_iterate_range() to mark individual chunk. Unfortunately, oop_iterate_range() does not iterate over object klass metadata, so we end up missing the mark of object array klass metadata.

Thanks for @lmao (Liang Mao) reporting the bug.

• hotspot_gc_shenandoah

---

Progress

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Issue

• JDK-8257701: Shenandoah: objArrayKlass metadata is not marked with chunked arrays

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1602/head:pull/1602
$ git checkout pull/1602

[bridgekeeper]

👋 Welcome back zgu! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@zhengyu123 The following labels will be automatically applied to this pull request:

• hotspot-gc
• shenandoah

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[mlbridge]

Webrevs

• 00: Full (5eabd8b)

[shipilev]

Shenandoah change looks good. I wonder if G1 has the same bug! I think it does... Please submit a "potential bug" for it?

[openjdk]

@zhengyu123 This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8257701: Shenandoah: objArrayKlass metadata is not marked with chunked arrays

Reviewed-by: shade

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 18 new commits pushed to the master branch:

• 55f5542: 8026976: ECParameters, Point does not match field size
• d3f3c32: 8255742: PrintInlining as compiler directive doesn't print virtual calls
• 6c9482e: 8257561: Some code is not vectorized after 8251925 and 8250607
• 70517c8: 8257642: CipherByteBufferOverwriteTest copyright issue
• e836396: 8257436: [aarch64] Regressions in ArrayCopyUnalignedDst.testByte/testChar for 65-78 bytes when UseSIMDForMemoryOps is on
• b170c83: 8257591: Remove suppression of record preview related warnings in java.lang
• 66a2e70: 8255845: Memory leak in imageFile.cpp
• fa58671: 8257020: [JVMCI] enable a JVMCICompiler to specify which GCs it supports
• 129c377: 8257594: C2 compiled checkcast of non-null object triggers endless deoptimization/recompilation cycle
• e4497c9: 8256718: Obsolete the long term deprecated and aliased Trace flags
• ... and 8 more: https://git.openjdk.java.net/jdk/compare/cc1915b3b320d9729772a81642cf5ca6563094cd...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[zhengyu123]

Shenandoah change looks good. I wonder if G1 has the same bug! I think it does... Please submit a "potential bug" for it?

G1 does things a little different, for each array slice (chunk), it calls obj->oop_iterate(closure, MemRegion), in turn, maps to ObjArrayKlass::oop_oop_iterate_bounded(obj, closure, MemRegion), which does walk over metadata.

[zhengyu123]

/integrate

[openjdk]

@zhengyu123 Since your change was applied there have been 21 commits pushed to the master branch:

• 2b73f99: 8228615: Optional.empty doc should suggest using isEmpty
• 805d058: 8254699: Suboptimal PreTouchParallelChunkSize defaults and limits
• e29ee5b: 8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false
• 55f5542: 8026976: ECParameters, Point does not match field size
• d3f3c32: 8255742: PrintInlining as compiler directive doesn't print virtual calls
• 6c9482e: 8257561: Some code is not vectorized after 8251925 and 8250607
• 70517c8: 8257642: CipherByteBufferOverwriteTest copyright issue
• e836396: 8257436: [aarch64] Regressions in ArrayCopyUnalignedDst.testByte/testChar for 65-78 bytes when UseSIMDForMemoryOps is on
• b170c83: 8257591: Remove suppression of record preview related warnings in java.lang
• 66a2e70: 8255845: Memory leak in imageFile.cpp
• ... and 11 more: https://git.openjdk.java.net/jdk/compare/cc1915b3b320d9729772a81642cf5ca6563094cd...master

Your commit was automatically rebased without conflicts.

Pushed as commit 7c7facc.

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