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8257073: ZGC: Try forward object before retaining page #1431

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pliden
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@pliden pliden commented Nov 25, 2020

This is a follow up to @albertnetymk's comment in the review of #1228, where he suggested that we could try to forward the object before we go ahead and retain the page. This could be an optimization in two cases:

  1. A mutator would avoid a relocation stall in case the page is claimed, but the object the mutator is interested in has already been relocated.
  2. The worker thread detaching the page would not have to wait for a mutator that is just forwarding an object.

Progress

  • Change must not contain extraneous whitespace
  • Commit message must refer to an issue
  • Change must be properly reviewed

Testing

Linux x64 Linux x86 Windows x64 macOS x64
Build (6/6 failed) (2/2 failed) ✔️ (2/2 passed) ✔️ (2/2 passed)
Test (tier1) ✔️ (9/9 passed) ✔️ (9/9 passed)

Failed test tasks

Issue

  • JDK-8257073: ZGC: Try forward object before retaining page

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$ git fetch https://git.openjdk.java.net/jdk pull/1431/head:pull/1431
$ git checkout pull/1431

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@bridgekeeper bridgekeeper bot commented Nov 25, 2020

👋 Welcome back pliden! 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 Nov 25, 2020
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@openjdk openjdk bot commented Nov 25, 2020

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

  • hotspot-gc

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 pull request command.

@openjdk openjdk bot added the hotspot-gc label Nov 25, 2020
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@mlbridge mlbridge bot commented Nov 25, 2020

Webrevs

fisk
fisk approved these changes Nov 26, 2020
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@fisk fisk left a comment

Looks good.

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@openjdk openjdk bot commented Nov 26, 2020

@pliden 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:

8257073: ZGC: Try forward object before retaining page

Reviewed-by: ayang, eosterlund, stefank

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 42 new commits pushed to the master branch:

  • 1b3aa3a: 8256831: MIPS Zero builds fail with undefined __atomic_compare_exchange_8
  • 734d3c3: 8256862: Several java/foreign tests fail on x86_32 platforms
  • 7946c94: 8257082: ZGC: Clean up ZRuntimeWorkers and ZWorkers
  • f6d6a07: 8256938: Improve remembered set sampling task scheduling
  • b823ad9: 8257072: ZGC: Rename roots iterators
  • 973255c: 8196100: javax/swing/text/JTextComponent/5074573/bug5074573.java fails
  • a8e3eab: 8245026: PsAdaptiveSizePolicy::_old_gen_policy_is_ready is unused
  • b1d1499: 8256956: RegisterImpl::max_slots_per_register is incorrect on AMD64
  • 20020d1: 8254360: Re-examine use of CodeBuffer::verify_section_allocation
  • e56a8df: 8257042: [aix] Disable os.release_one_mapping_multi_commits_vm gtest
  • ... and 32 more: https://git.openjdk.java.net/jdk/compare/7b3d0958c068c8f45c98ea0615ef8cd908fd408d...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 Nov 26, 2020
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@pliden pliden commented Nov 26, 2020

Thanks for reviewing!

/integrate

@openjdk openjdk bot closed this Nov 26, 2020
@openjdk openjdk bot added integrated and removed ready rfr labels Nov 26, 2020
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@openjdk openjdk bot commented Nov 26, 2020

@pliden Since your change was applied there have been 42 commits pushed to the master branch:

  • 1b3aa3a: 8256831: MIPS Zero builds fail with undefined __atomic_compare_exchange_8
  • 734d3c3: 8256862: Several java/foreign tests fail on x86_32 platforms
  • 7946c94: 8257082: ZGC: Clean up ZRuntimeWorkers and ZWorkers
  • f6d6a07: 8256938: Improve remembered set sampling task scheduling
  • b823ad9: 8257072: ZGC: Rename roots iterators
  • 973255c: 8196100: javax/swing/text/JTextComponent/5074573/bug5074573.java fails
  • a8e3eab: 8245026: PsAdaptiveSizePolicy::_old_gen_policy_is_ready is unused
  • b1d1499: 8256956: RegisterImpl::max_slots_per_register is incorrect on AMD64
  • 20020d1: 8254360: Re-examine use of CodeBuffer::verify_section_allocation
  • e56a8df: 8257042: [aix] Disable os.release_one_mapping_multi_commits_vm gtest
  • ... and 32 more: https://git.openjdk.java.net/jdk/compare/7b3d0958c068c8f45c98ea0615ef8cd908fd408d...master

Your commit was automatically rebased without conflicts.

Pushed as commit bf66d73.

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

@pliden pliden deleted the 8257073_try_forward_before_retain branch Nov 26, 2020
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