JDK-8266802: Shenandoah: Round up region size to page size unconditionally

[shipilev]

Since JDK-8265239, runtime/os/TestTracePageSizes.java fails with Shenandoah like this:

# Internal Error (/home/buildbot/worker/test-jdkX-linux/build/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp:156), pid=55712, tid=55720
# assert(_num_regions == (max_byte_size / reg_size_bytes)) failed: Must match

This is because Shenandoah region sizes are rounded up to page size only when ShenandoahUncommit is true. In the failing test configuration, ShenandoahUncommit is false, because Xmx == Xms.

Additional testing:

• New regression test, now passes
• tier1 with Shenandoah

---

Progress

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• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8266802: Shenandoah: Round up region size to page size unconditionally

Reviewers

• Zhengyu Gu (@zhengyu123 - Reviewer) ⚠️ Review applies to 96a4778

Reviewing

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$ git checkout pull/3945
$ git pull https://git.openjdk.java.net/jdk pull/3945/head

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$ git pr checkout 3945

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https://git.openjdk.java.net/jdk/pull/3945.diff

[bridgekeeper]

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[openjdk]

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

• hotspot-gc
• shenandoah

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 02: Full - Incremental (dd3ba65d)
• 01: Full - Incremental (96a4778b)
• 00: Full (94d4f023)

[zhengyu123]

I filed JDK-8266740, that is related. I believe we should defer region count calculation after heap size adjustment to avoid miscalculating the value. Do you think we should consolidate the 2 CRs?

[zhengyu123]

I filed JDK-8266740, that is related. I believe we should defer region count calculation after heap size adjustment to avoid miscalculating the value. Do you think we should consolidate the 2 CRs?

Never mind. Your change looks good. I will make JDK-8266740 a dup.

[zhengyu123]

Looks good

[openjdk]

@shipilev 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:

8266802: Shenandoah: Round up region size to page size unconditionally

Reviewed-by: zgu

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 4 new commits pushed to the master branch:

• de78431: 8241502: C2: Migrate x86_64.ad to MacroAssembler
• c8b7447: 8266603: jpackage: Add missing copyright file in Java runtime .deb installers
• c494efc: 8266774: System property values for stdout/err on Windows UTF-8
• 25d99e5: 8266330: itableMethodEntry::initialize() asserts with archived old classes

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

[shipilev]

I filed JDK-8266740, that is related. I believe we should defer region count calculation after heap size adjustment to avoid miscalculating the value. Do you think we should consolidate the 2 CRs?

Oh, I have not seen that. Yes, I reckon doing the way this PR approaches it is cleaner. I'll integrate once tests are green.

[shipilev]

/integrate

[openjdk]

@shipilev Since your change was applied there have been 7 commits pushed to the master branch:

• 8851cb6: 8266779: Use instead of ZERO_WIDTH_SPACE
• 0cc7833: 8265208: [JEP-356] : SplittableRandom and SplittableGenerators - splits() methods does not throw NullPointerException when source is null
• f78440a: 8266440: Shenandoah: TestReferenceShortcutCycle.java test failed on AArch64
• de78431: 8241502: C2: Migrate x86_64.ad to MacroAssembler
• c8b7447: 8266603: jpackage: Add missing copyright file in Java runtime .deb installers
• c494efc: 8266774: System property values for stdout/err on Windows UTF-8
• 25d99e5: 8266330: itableMethodEntry::initialize() asserts with archived old classes

Your commit was automatically rebased without conflicts.

Pushed as commit e5d3ee3.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

[zhengyu123]

/backport jdk16u

[openjdk]

@zhengyu123 Unknown command backport - for a list of valid commands use /help.