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8328168: Epsilon: Premature OOM when allocating object larger than uncommitted heap size #18304

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@lgxbslgx lgxbslgx commented Mar 14, 2024

Hi all,

When an object size meets the following three conditions, the allocation will fail unexpectedly.

  1. object_size > uncommitted_size
  2. object_size > committed_but_unused_size
  3. object_size < unused_size (unused_size equals uncommitted_size + committed_but_unused_size)

Please read the newly added test of this patch for the concrete case.

Thanks for taking the time to review.

Best Regrads,
-- Guoxiong


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  • JDK-8328168: Epsilon: Premature OOM when allocating object larger than uncommitted heap size (Bug - P2)

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bridgekeeper bot commented Mar 14, 2024

👋 Welcome back gli! A progress list of the required criteria for merging this PR into pr/18303 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 bot commented Mar 14, 2024

@lgxbslgx 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:

8328168: Epsilon: Premature OOM when allocating object larger than uncommitted heap size

Reviewed-by: shade, tschatzl

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:

  • c342188: 8328074: Add jcheck whitespace checking for assembly files
  • 3c70f26: 8328112: Remove CardTable::_guard_region
  • 48717d6: 8326333: jshell completion on arrays is incomplete
  • ece4124: 8328247: Remove redundant dir for tests converted from applet to main
  • d32ce65: 8327651: Rename DictionaryEntry members related to protection domain
  • 0719419: 8328236: module_entry in CDS map file has stale value
  • 0204aac: 8328115: Convert java/awt/font/TextLayout/TestJustification.html applet test to main
  • 9bc1b06: 8328242: Add a log area to the PassFailJFrame
  • 65a84c2: 8328006: refactor large anonymous inner class in HtmlDocletWriter
  • 044f4ed: 8326979: (jdeps) improve the error message for FindException caused by InvalidModuleDescriptorException
  • ... and 3 more: https://git.openjdk.org/jdk/compare/90ab52e598f74ed872fe404130d57f6596430727...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 changed the title JDK-8328168 8328168: Epsilon: 'EpsilonHeap::allocate_work' can't allocate an object larger than the uncommitted size Mar 14, 2024
@openjdk openjdk bot added the rfr Pull request is ready for review label Mar 14, 2024
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openjdk bot commented Mar 14, 2024

@lgxbslgx 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 hotspot-gc-dev@openjdk.org label Mar 14, 2024
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mlbridge bot commented Mar 14, 2024

Webrevs

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Oh. So the critical change is here:

} else if (size_in_bytes < unused_space) {
  // No space to expand in bulk, and this allocation is still possible,
  // take all the remaining space:

Before this fix, we might have had some unused, but already expanded space. But we would miss this, since we only checked how much there was left to expand to. Which means we still have space to afford the allocations, we instead we just throw a premature OOM. Whoops.

I suggest we rename the issue to Epsilon: Premature OOM when allocating object larger than uncommitted heap size.

test/hotspot/jtreg/gc/epsilon/TestEnoughUnusedSpace.java Outdated Show resolved Hide resolved
test/hotspot/jtreg/gc/epsilon/TestEnoughUnusedSpace.java Outdated Show resolved Hide resolved
src/hotspot/share/gc/epsilon/epsilonHeap.cpp Show resolved Hide resolved
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(meant to request changes)

@lgxbslgx lgxbslgx changed the title 8328168: Epsilon: 'EpsilonHeap::allocate_work' can't allocate an object larger than the uncommitted size 8328168: Epsilon: Premature OOM when allocating object larger than uncommitted heap size Mar 15, 2024
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openjdk bot commented Mar 15, 2024

⚠️ @lgxbslgx This pull request contains merges that bring in commits not present in the target repository. Since this is not a "merge style" pull request, these changes will be squashed when this pull request in integrated. If this is your intention, then please ignore this message. If you want to preserve the commit structure, you must change the title of this pull request to Merge <project>:<branch> where <project> is the name of another project in the OpenJDK organization (for example Merge jdk:master).

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lgxbslgx commented Mar 15, 2024

⚠️ @lgxbslgx This pull request contains merges that bring in commits not present in the target repository. Since this is not a "merge style" pull request, these changes will be squashed when this pull request in integrated. If this is your intention, then please ignore this message. If you want to preserve the commit structure, you must change the title of this pull request to Merge <project>:<branch> where <project> is the name of another project in the OpenJDK organization (for example Merge jdk:master).

This problem can be solved after #18303 integrating. I shouldn't have merged the master so quickly.

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The parent pull request that this pull request depends on has now been integrated and the target branch of this pull request has been updated. This means that changes from the dependent pull request can start to show up as belonging to this pull request, which may be confusing for reviewers. To remedy this situation, simply merge the latest changes from the new target branch into this pull request by running commands similar to these in the local repository for your personal fork:

git checkout FAILED-ALLOCATION
git fetch https://git.openjdk.org/jdk.git master
git merge FETCH_HEAD
# if there are conflicts, follow the instructions given by git merge
git commit -m "Merge master"
git push

# Conflicts:
#	src/hotspot/share/gc/epsilon/epsilonHeap.cpp
@lgxbslgx lgxbslgx requested a review from shipilev March 18, 2024 05:09
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This looks fine, thanks.

src/hotspot/share/gc/epsilon/epsilonHeap.cpp Show resolved Hide resolved
@openjdk openjdk bot added the ready Pull request is ready to be integrated label Mar 18, 2024
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@shipilev Thanks for your review. Waiting for another review.

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@shipilev @tschatzl Thanks for the review.

/integrate

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openjdk bot commented Mar 18, 2024

Going to push as commit 7baec66.
Since your change was applied there have been 13 commits pushed to the master branch:

  • c342188: 8328074: Add jcheck whitespace checking for assembly files
  • 3c70f26: 8328112: Remove CardTable::_guard_region
  • 48717d6: 8326333: jshell completion on arrays is incomplete
  • ece4124: 8328247: Remove redundant dir for tests converted from applet to main
  • d32ce65: 8327651: Rename DictionaryEntry members related to protection domain
  • 0719419: 8328236: module_entry in CDS map file has stale value
  • 0204aac: 8328115: Convert java/awt/font/TextLayout/TestJustification.html applet test to main
  • 9bc1b06: 8328242: Add a log area to the PassFailJFrame
  • 65a84c2: 8328006: refactor large anonymous inner class in HtmlDocletWriter
  • 044f4ed: 8326979: (jdeps) improve the error message for FindException caused by InvalidModuleDescriptorException
  • ... and 3 more: https://git.openjdk.org/jdk/compare/90ab52e598f74ed872fe404130d57f6596430727...master

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Mar 18, 2024
@openjdk openjdk bot closed this Mar 18, 2024
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Mar 18, 2024
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openjdk bot commented Mar 18, 2024

@lgxbslgx Pushed as commit 7baec66.

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

@lgxbslgx lgxbslgx deleted the FAILED-ALLOCATION branch March 18, 2024 11:36
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