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8268458: Add verification type for evacuation failures #4473

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tschatzl
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@tschatzl tschatzl commented Jun 11, 2021

Hi all,

can I have reviews for this change that adds a new verification type (argument for -XX:VerifyGCType for G1) that only enables verification after an evacuation failure?

The reasons is that time and time again we have issues with evacuation failure as it's by far not tested as much as regular collection, and reproducing issues then is often hampered by that there is no way to just verify after verification failure. Enabling it just for all young collections is possible, but typically does not help much.

Fwiw, this change requires a small semantics change in how the current VerifyGCType is compared to the one stored as active (i.e. in G1HeapVerifier::_enabled_verification_types). Since the situations that can be enabled are not distinct any more (any young gc can have an evacuation failure), the existing check for a given set bit in G1HeapVerifier::should_verify() does not work any more.

This also means that the previous assumption that G1VerifyType::G1VerifyAll is not the same as all flags enabled can not be checked any more. I do not think this is any loss in functionality (see the gtests for removed checks).

The same functionality could also have been implemented by injecting all of the young gen type bits into the existing type on evacuation failure at the cost of remembering that the user selected evacuation failures for evacuation somewhere else. Not sure if that would be simpler.

Testing: tier1-2 (still running), updated test

Thanks,
Thomas


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  • JDK-8268458: Add verification type for evacuation failures

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Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.java.net/jdk pull/4473/head:pull/4473
$ git checkout pull/4473

Update a local copy of the PR:
$ git checkout pull/4473
$ git pull https://git.openjdk.java.net/jdk pull/4473/head

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Checkout this PR locally:
$ git pr checkout 4473

View PR using the GUI difftool:
$ git pr show -t 4473

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Download this PR as a diff file:
https://git.openjdk.java.net/jdk/pull/4473.diff

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@bridgekeeper bridgekeeper bot commented Jun 11, 2021

👋 Welcome back tschatzl! 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.

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@openjdk openjdk bot commented Jun 11, 2021

@tschatzl 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 Jun 11, 2021
@tschatzl
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@tschatzl tschatzl commented Jun 11, 2021

This change helped a lot with JDK-8267073.

@tschatzl tschatzl force-pushed the submit/8268458-young-evac-failure-verifygctype branch from 938fb8b to b03fe64 Compare Jun 11, 2021
@tschatzl tschatzl marked this pull request as ready for review Jun 14, 2021
@openjdk openjdk bot added the rfr label Jun 14, 2021
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@mlbridge mlbridge bot commented Jun 14, 2021

Webrevs

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@kimbarrett kimbarrett left a comment

Looks good.

G1VerifyType seems poorly named. The name suggests a single value, but it's really a selection bitmask. Perhaps a followup RFE?

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@openjdk openjdk bot commented Jun 19, 2021

@tschatzl 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:

8268458: Add verification type for evacuation failures

Reviewed-by: kbarrett, iwalulya

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At the time when this comment was updated there had been 115 new commits pushed to the master branch:

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@openjdk openjdk bot added the ready label Jun 19, 2021
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@tschatzl tschatzl commented Jun 21, 2021

Thanks @kimbarrett for your review. I agree that we should probably rename that flag, I'll file an RFE

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@tschatzl tschatzl commented Jun 21, 2021

Thanks @kimbarrett @walulyai for your reviews.

Integrate

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@tschatzl tschatzl commented Jun 21, 2021

/integrate

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@openjdk openjdk bot commented Jun 21, 2021

Going to push as commit cd20c01.
Since your change was applied there have been 117 commits pushed to the master branch:

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot closed this Jun 21, 2021
@openjdk openjdk bot added integrated and removed ready rfr labels Jun 21, 2021
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@openjdk openjdk bot commented Jun 21, 2021

@tschatzl Pushed as commit cd20c01.

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

@tschatzl tschatzl deleted the submit/8268458-young-evac-failure-verifygctype branch Jun 21, 2021
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