8252889: Obsolete -XX:+InsertMemBarAfterArraycopy

[TobiHartmann]

The InsertMemBarAfterArraycopy product flag (enabled by default) is broken. I propose to simply remove it.
The corresponding CSR (JDK-8252890) is still waiting for approval.

Thanks,
Tobias

---

Progress

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Issue

• JDK-8252889: Obsolete -XX:+InsertMemBarAfterArraycopy

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer)
• Aditya Mandaleeka (@adityamandaleeka - Author)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/69/head:pull/69
$ git checkout pull/69

[bridgekeeper]

👋 Welcome back thartmann! 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]

@TobiHartmann The following label will be automatically applied to this pull request: hotspot.

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

[mlbridge]

Webrevs

• 00: Full (ee33d8e)

[shipilev]

Synopsis might be changed to "Obsolete -XX:+InsertMemBarAfterArraycopy".

[openjdk]

@TobiHartmann This change now passes all automated pre-integration checks. In addition to the automated checks, the change must also fulfill all project specific requirements

After integration, the commit message will be:

8252889: Obsolete -XX:+InsertMemBarAfterArraycopy

Reviewed-by: shade, adityam

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Since the source branch of this PR was last updated there have been 19 commits pushed to the master branch:

• f933961: 8252980: comment only changes extracted from JDK-8247281
• 4333942: 8250217: com.sun.tools.javac.api.JavacTaskImpl swallows compiler exceptions potentially producing false positive test results
• 5166094: 8252957: Wrong comment in CgroupV1Subsystem::cpu_quota
• 6329de4: 8248532: Every time I change keyboard language at my MacBook, Java crashes
• d560964: 8252794: Creation of JNIMethodBlock should be done with a leaf lock
• 5fef8dd: 8235229: Compilation against a modular, multi-release JAR erroneous with --release
• 382b8fe: 8240751: Shenandoah: fold ShenandoahTracer definition
• c98417e: 8250840: some tests use --enable-preview unnecessarily
• c655b70: 8252916: Newline in object field values list of ScopeDesc should be removed
• 30fa8d5: 8157729: examples in LinkedHashMap and LinkedHashSet class doc use raw types
• ... and 9 more: https://git.openjdk.java.net/jdk/compare/73ba3ae1f5f5bfb0cc5cf9733ffa5c4a44508777...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid automatic rebasing, please merge master into your branch, and then specify the current head hash when integrating, like this: /integrate f9339616e1c3ee01b3212b95fa017a0f52a07977.

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

[TobiHartmann]

Thanks for the review, Aleksey!

[mlbridge]

Mailing list message from David Holmes on hotspot-dev:

Hi Aleksey,

On 8/09/2020 8:23 pm, Aleksey Shipilev wrote:

On Tue, 8 Sep 2020 10:04:35 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

The InsertMemBarAfterArraycopy product flag (enabled by default) is broken. I propose to simply remove it.
The corresponding CSR (JDK-8252890) is still waiting for approval.

Thanks,
Tobias

Synopsis might be changed to "Obsolete -XX:+InsertMemBarAfterArraycopy".

src/hotspot/share/runtime/arguments.cpp line 556:

554: { "UseSemaphoreGCThreadsSynchronization", JDK_Version::undefined(), JDK_Version::jdk(16), JDK_Version::jdk(17) },
555: { "ForceNUMA", JDK_Version::jdk(15), JDK_Version::jdk(16), JDK_Version::jdk(17) },
556: { "InsertMemBarAfterArraycopy", JDK_Version::undefined(), JDK_Version::jdk(16), JDK_Version::jdk(17) },

This seems like a product flag, so needs to follow `ForceNUMA` example? E.g. 16 -> 17 -> 18? And a provisional CSR?

Product flags can be directly obsoleted without being deprecated first
if they are basically non-functional, as this one seems to be.

Cheers,
David
-----

[adityamandaleeka]

Not a reviewer, but this looks good to me.

[TobiHartmann]

Thanks for the review!

[TobiHartmann]

/integrate

[openjdk]

@TobiHartmann Since your change was applied there have been 19 commits pushed to the master branch:

• f933961: 8252980: comment only changes extracted from JDK-8247281
• 4333942: 8250217: com.sun.tools.javac.api.JavacTaskImpl swallows compiler exceptions potentially producing false positive test results
• 5166094: 8252957: Wrong comment in CgroupV1Subsystem::cpu_quota
• 6329de4: 8248532: Every time I change keyboard language at my MacBook, Java crashes
• d560964: 8252794: Creation of JNIMethodBlock should be done with a leaf lock
• 5fef8dd: 8235229: Compilation against a modular, multi-release JAR erroneous with --release
• 382b8fe: 8240751: Shenandoah: fold ShenandoahTracer definition
• c98417e: 8250840: some tests use --enable-preview unnecessarily
• c655b70: 8252916: Newline in object field values list of ScopeDesc should be removed
• 30fa8d5: 8157729: examples in LinkedHashMap and LinkedHashSet class doc use raw types
• ... and 9 more: https://git.openjdk.java.net/jdk/compare/73ba3ae1f5f5bfb0cc5cf9733ffa5c4a44508777...master

Your commit was automatically rebased without conflicts.

Pushed as commit f78f780.

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