8314573: G1: Heap resizing at Remark does not take existing eden regions into account

[mmyxym]

Clean backport of fix of G1 Heap resizing heuristics at remark

Additional testing:

• Linux aarch64 server release/fastdebug, test/hotspot/jtreg/gc with +UseG1GC

---

Progress

• JDK-8314573 needs maintainer approval
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8314573: G1: Heap resizing at Remark does not take existing eden regions into account (Bug - P3 - Approved)

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[openjdk]

@mmyxym 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:

8314573: G1: Heap resizing at Remark does not take existing eden regions into account

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At the time when this comment was updated there had been 121 new commits pushed to the master branch:

• 56a9090: 8312014: [s390x] TestSigInfoInHsErrFile.java Failure
• c922c50: 8322962: Upcall stub might go undetected when freezing frames
• cbd30c9: 8325095: C2: bailout message broken: ResourceArea allocated string used after free
• 75ac9e8: 8328168: Epsilon: Premature OOM when allocating object larger than uncommitted heap size
• a0e8de8: 8330156: RISC-V: Range check auipc + signed 12 imm instruction
• e7ebae5: 8321713: Harmonize executeTestJvm with create[Limited]TestJavaProcessBuilder
• d8bc9e4: 8331113: createJMHBundle.sh support configurable maven repo mirror
• d1b97d4: 8309142: Refactor test/langtools/tools/javac/versions/Versions.java
• e59f4fa: 8328194: Add a test to check default rendering engine
• 6f07ee4: 8324733: [macos14] Problem list tests which fail due to macOS bug described in JDK-8322653
• ... and 111 more: https://git.openjdk.org/jdk21u-dev/compare/6791646b9f9673ea36a67e5af7584929dfb16069...master

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[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @mmyxym This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (07917054)

[mmyxym]

/approval request Clean backport of fix of G1 Heap resizing heuristics at remark. Risk is low which only affects the heuristics.

[openjdk]

@mmyxym
8314573: The approval request has been created successfully.

[GoeLin]

Hi @mmyxym, I don't think the risk is that low.
After all, someone opened JDK-8315866 because his GC behaved differently. Something like this can obstruct a producitve system.

[jerboaa]

I agree with @GoeLin. @mmyxym Please explain in more detail why you think this backport is needed for JDK 21u. The explanation given isn't very convincing. We'd be trading (potentially) more cpu cycles for (potentially) less use of memory.

[mmyxym]

@GoeLin ，@jerboaa，I have noticed the original issue that heap resizing counted eden region size since the original JEP346 arrived in JDK12. The heap resizing heuristics in G1 remark Pause is similar to the one in Full GC which will estimate the heap capacity based on live set size. But counting of eden region size as part of live set will make the resizing behavior unexpected due to random eden use at remark pause . Only counting old objects as live set is more reasonable. As @tschatzl described in JDK-8315866, the behavior is expected which uses less memory for more gc activity.

[mmyxym]

/integrate

[openjdk]

@mmyxym
Your change (at version 0791705) is now ready to be sponsored by a Committer.

[mmyxym]

Hi, could any committers help with the integration? Thanks.

[zhengyu123]

/sponsor

[openjdk]

Going to push as commit 93d091a.
Since your change was applied there have been 141 commits pushed to the master branch:

• 41fda4a: 8319376: ParallelGC: Forwarded objects found during heap inspection
• ec6b326: 8310913: Move ReferencedKeyMap to jdk.internal so it may be shared
• 92b43c5: 8317007: Add bulk removal of dead nmethods during class unloading
• ed2f5a8: 8310228: Improve error reporting for uncaught native exceptions on Windows
• 7a400f2: 8309890: TestStringDeduplicationInterned.java waits for the wrong condition
• 16ba673: 8331639: [21u]: Bump GHA bootstrap JDK to 21.0.3
• 2b858f5: 8328938: C2 SuperWord: disable vectorization for large stride and scale
• 9159882: 8310513: [s390x] Intrinsify recursive ObjectMonitor locking
• 3ff5359: 8330011: [s390x] update block-comments to make code consistent
• abbad92: 8326201: [S390] Need to bailout cleanly if creation of stubs fails when code cache is out of space
• ... and 131 more: https://git.openjdk.org/jdk21u-dev/compare/6791646b9f9673ea36a67e5af7584929dfb16069...master

Your commit was automatically rebased without conflicts.

[openjdk]

@zhengyu123 @mmyxym Pushed as commit 93d091a.

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