8254075: Shenandoah: Remove ShenandoahCodeRootsStyle diagnostic flag and related test

[zhengyu123]

Shenandoah introduced fast code roots iteration (ShenandoahCodeRootsStyle = 2), also kept 2 additional iteration mechanism (ShenandoahCodeRootsStyle = 0 and 1), mainly for verification purpose.

Today, Shenandoah normally iterates code roots concurrently using style 2, while style 0 and 1 require safepoints, that makes style 0 and 1 verification less useful. Besides, Shenandoah has much improved verifier, more suitable for the purpose.

Let's remove this diagnostic flag and related test.

Test:

• hotspot_gc_shenandoah

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
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Issue

• JDK-8254075: Shenandoah: Remove ShenandoahCodeRootsStyle diagnostic flag and related test

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/524/head:pull/524
$ git checkout pull/524

[bridgekeeper]

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[openjdk]

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

• hotspot-gc
• shenandoah

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[mlbridge]

Webrevs

• 01: Full - Incremental (093a63a)
• 00: Full (834fed1)

[shipilev]

Looks fine to me, except ClassUnloading handling in one place.

[shipilev]

Hold on, this used to check ClassUnloading, should it continue to check it?

[zhengyu123]

No. I actually puzzled why checked it here, our concurrent roots scanner can handle both scenarios.
Maybe a leftover from concurrent roots to concurrent class unloading transition?

[shipilev]

It is maybe something that disables concurrent class unloading when -ClassUnloading is specified? Although it should have been handled in shenandoahArguments.cpp. Still, I'd prefer to leave the behavior exact, and then remove the ClassUnloading reference in a separate PR.

[zhengyu123]

Make sense, updated.

[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 more details.

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

8254075: Shenandoah: Remove ShenandoahCodeRootsStyle diagnostic flag and related test

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 7 new commits pushed to the master branch:

• d2b1dc6: 8254054: Pre-submit testing using GitHub Actions should not use the deprecated set-env command
• a34f48b: 8253832: CharsetDecoder : decode() mentioning CoderMalfunctionError behavior not as per spec
• f397b60: 8251123: doclint warnings about missing javadoc tags and comments
• c9d1dcc: 8253902: G1: Starting a new marking cycle before the conc mark thread fully completed causes assertion failure
• 9199783: 8253565: PPC64: Fix duplicate if condition in vm_version_ppc.cpp
• 1728547: 8254010: GrowableArrayView::print fails to compile
• 6e61861: 8254046: Remove double semicolon introduced by JDK-8235521

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.

[zhengyu123]

/integrate

[openjdk]

@zhengyu123 Since your change was applied there have been 9 commits pushed to the master branch:

• 77921b9: 8254080: fix for JDK-8204256 causes jlink test failures
• 57493c1: 8253694: Remove Thread::muxAcquire() from ThreadCrashProtection()
• d2b1dc6: 8254054: Pre-submit testing using GitHub Actions should not use the deprecated set-env command
• a34f48b: 8253832: CharsetDecoder : decode() mentioning CoderMalfunctionError behavior not as per spec
• f397b60: 8251123: doclint warnings about missing javadoc tags and comments
• c9d1dcc: 8253902: G1: Starting a new marking cycle before the conc mark thread fully completed causes assertion failure
• 9199783: 8253565: PPC64: Fix duplicate if condition in vm_version_ppc.cpp
• 1728547: 8254010: GrowableArrayView::print fails to compile
• 6e61861: 8254046: Remove double semicolon introduced by JDK-8235521

Your commit was automatically rebased without conflicts.

Pushed as commit 51fdb4c.

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