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8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false #1600

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@zhengyu123
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@zhengyu123 zhengyu123 commented Dec 3, 2020

Since Shenandoah GC safepoints are scheduled by control thread, so that, if querying comes from control thread, the answer should be false.

is_at_shenandoah_safepoint() is still not reliable, even after JDK-8253778, we may consider to scratch it.

  • hotspot_gc_shenandoah x86_64 and x86_32

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  • JDK-8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false

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$ git fetch https://git.openjdk.java.net/jdk pull/1600/head:pull/1600
$ git checkout pull/1600

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@bridgekeeper bridgekeeper bot commented Dec 3, 2020

👋 Welcome back zgu! 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 openjdk bot added the rfr label Dec 3, 2020
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@openjdk openjdk bot commented Dec 3, 2020

@zhengyu123 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.

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@mlbridge mlbridge bot commented Dec 3, 2020

Webrevs

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@shipilev shipilev left a comment

This looks good, consider fixing a few nits below.

public:
ShenandoahControlThread* control_thread() const { return _control_thread; }

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@shipilev shipilev Dec 3, 2020

Maybe it is easier to friend the class that wants it, instead of exposing the control thread for everyone?

// Shenandoah GC specific safepoints are scheduled by control thread,
// so that, querying from control thread can not happen during those
// safepoints.
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@shipilev shipilev Dec 3, 2020

Consider this wording:

    // Shenandoah GC specific safepoints are scheduled by control thread.
    // So if we are enter here from control thread, then we are definitely not
    // at Shenandoah safepoint, but at something else.

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@zhengyu123 zhengyu123 Dec 3, 2020

Updated accordingly.

Thanks, Aleksey.

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@openjdk openjdk bot commented Dec 3, 2020

@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 details.

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

8257641: Shenandoah: Query is_at_shenandoah_safepoint() from control thread should return false

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 13 new commits pushed to the master branch:

  • b170c83: 8257591: Remove suppression of record preview related warnings in java.lang
  • 66a2e70: 8255845: Memory leak in imageFile.cpp
  • fa58671: 8257020: [JVMCI] enable a JVMCICompiler to specify which GCs it supports
  • 129c377: 8257594: C2 compiled checkcast of non-null object triggers endless deoptimization/recompilation cycle
  • e4497c9: 8256718: Obsolete the long term deprecated and aliased Trace flags
  • 4a267f1: 8244847: Linux/PPC: runtime/CompressedOops/CompressedClassPointers: smallHeapTest fails
  • b44a329: 8256864: [windows] Improve tracing for mapping errors
  • ae1eb28: 8257604: JNI_ArgumentPusherVaArg leaks valist
  • 4169d96: 8257143: Enable JVMCI code installation tests on AArch64
  • a5a034b: 8257617: TestLinkPlatform fails with new Java source version
  • ... and 3 more: https://git.openjdk.java.net/jdk/compare/cc1915b3b320d9729772a81642cf5ca6563094cd...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.

@openjdk openjdk bot added the ready label Dec 3, 2020
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@shipilev shipilev left a comment

Looks good.

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@zhengyu123 zhengyu123 commented Dec 3, 2020

/integrate

@openjdk openjdk bot closed this Dec 3, 2020
@openjdk openjdk bot added integrated and removed ready rfr labels Dec 3, 2020
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@openjdk openjdk bot commented Dec 3, 2020

@zhengyu123 Since your change was applied there have been 18 commits pushed to the master branch:

  • 55f5542: 8026976: ECParameters, Point does not match field size
  • d3f3c32: 8255742: PrintInlining as compiler directive doesn't print virtual calls
  • 6c9482e: 8257561: Some code is not vectorized after 8251925 and 8250607
  • 70517c8: 8257642: CipherByteBufferOverwriteTest copyright issue
  • e836396: 8257436: [aarch64] Regressions in ArrayCopyUnalignedDst.testByte/testChar for 65-78 bytes when UseSIMDForMemoryOps is on
  • b170c83: 8257591: Remove suppression of record preview related warnings in java.lang
  • 66a2e70: 8255845: Memory leak in imageFile.cpp
  • fa58671: 8257020: [JVMCI] enable a JVMCICompiler to specify which GCs it supports
  • 129c377: 8257594: C2 compiled checkcast of non-null object triggers endless deoptimization/recompilation cycle
  • e4497c9: 8256718: Obsolete the long term deprecated and aliased Trace flags
  • ... and 8 more: https://git.openjdk.java.net/jdk/compare/cc1915b3b320d9729772a81642cf5ca6563094cd...master

Your commit was automatically rebased without conflicts.

Pushed as commit e29ee5b.

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

@zhengyu123 zhengyu123 deleted the JDK-8257641-sh-sfpt-ctrl-thread branch Dec 3, 2020
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