8304015: G1: Metaspace-induced GCs should not trigger maximal compaction

[walulyai]

Hi all,

Please review this small cleanup to remove triggering maximal compaction on Metaspace-induced full-GCs.

Testing: Tier1.

---

Progress

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Issue

• JDK-8304015: G1: Metaspace-induced GCs should not trigger maximal compaction

Reviewers

• Albert Mingkun Yang (@albertnetymk - Reviewer)
• Thomas Schatzl (@tschatzl - Reviewer)

Reviewing

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk pull/12987/head

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$ git pr checkout 12987

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[openjdk]

@walulyai The following label will be automatically applied to this pull request:

• hotspot-gc

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[mlbridge]

Webrevs

• 00: Full (be9760b0)

[albertnetymk]

I think it's better to keep the var so that the semantic of the literal boolean is clear in this context.

(Slightly off the PR -- it's not obvious that metaspace related GC enters this path. Why isn't the decision on what GC cycle (young/old/clear-soft-or-not) to trigger made inside GC code?)

[openjdk]

@walulyai 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:

8304015: G1: Metaspace-induced GCs should not trigger maximal compaction

Reviewed-by: ayang, tschatzl

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 55 new commits pushed to the master branch:

• f835aaa: 8300727: java/awt/List/ListGarbageCollectionTest/AwtListGarbageCollectionTest.java failed with "List wasn't garbage collected"
• 466ffeb: 8303965: java.net.http.HttpClient should reset the stream if response headers contain malformed header fields
• 431e702: 8303213: Avoid AtomicReference in TextComponentPrintable
• 4cf4c59: 8303824: Parallel: Use more strict card table API
• 8e41bf2: 8303238: Create generalizations for existing LShift ideal transforms
• 805a4e6: 8303883: Confusing parameter name in G1UpdateRemSetTrackingBeforeRebuild::distribute_marked_bytes
• 25e7ac2: 8294966: Convert jdk.jartool/sun.tools.jar.FingerPrint to use the ClassFile API to parse JAR entries
• 3018b47: 8303969: Limit printed failures within an object during G1 heap verification
• b575e54: 8303963: Replace various encodings of UINT/SIZE_MAX in gc code
• c183fce: 8300926: Several startup regressions ~6-70% in 21-b6 all platforms
• ... and 45 more: https://git.openjdk.org/jdk/compare/713def0bf25c3488afb72e453f3b7cd09a909599...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.

[walulyai]

I think it's better to keep the var so that the semantic of the literal boolean is clear in this context.

Decided to go with using the comment /* do_maximal_compation */ as done in many other cases where we want to be clear but also avoid declaring variables.

(Slightly off the PR -- it's not obvious that metaspace related GC enters this path. Why isn't the decision on what GC cycle (young/old/clear-soft-or-not) to trigger made inside GC code?)

I think this is a design issue that we need to discuss along with other concerns around call paths to full-gc.

[walulyai]

Thanks @albertnetymk and @tschatzl for the reviews!

/integrate

[openjdk]

Going to push as commit 0cc0f06.
Since your change was applied there have been 65 commits pushed to the master branch:

• 43eca1d: 8303910: jdk/classfile/CorpusTest.java failed 1 of 6754 tests
• b6d70f2: 8303973: Library detection in runtime/ErrorHandling/TestDwarf.java fails on ppc64le RHEL8.5 for libpthread-2.28.so
• 2bb990e: 8301244: Tidy up compiler specific warnings files
• c073ef2: 8303482: Update LCMS to 2.15
• 49181b8: 8303955: RISC-V: Factor out the tmp parameter from copy_memory and copy_memory_v
• 7bbc5e0: 8300517: Refactor VisibleMemberTable (method members)
• a8f662e: 8303908: Add missing check in VTMS_transition_disable_for_all() for suspend mode
• 5685107: 8302491: NoClassDefFoundError omits the original cause of an error
• 671a452: 8303606: Memory leaks in Arguments::parse_each_vm_init_arg
• a95bc7a: 8294974: Convert jdk.jshell/jdk.jshell.execution.LocalExecutionControl to use the Classfile API to instrument classes
• ... and 55 more: https://git.openjdk.org/jdk/compare/713def0bf25c3488afb72e453f3b7cd09a909599...master

Your commit was automatically rebased without conflicts.

[openjdk]

@walulyai Pushed as commit 0cc0f06.

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