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JDK-8317987: C2 recompilations cause high memory footprint #16161

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tstuefe
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@tstuefe tstuefe commented Oct 12, 2023

While playing with the new compiler memory statistic (#16076), I saw that +StressRecompile causes a twofold increase in memory used during compilations.

Baseline:

highest peak during compilation is ~60 MB, caused by compilation of java/lang/invoke/LambdaForm$Kind::<clinit> with ~18k nodes.

./images/jdk/bin/java -XX:CompileCommand='collectmemstat,*.*' -XX:-StressRecompilation -Xcomp -Xbatch -cp $REPROS_JAR de.stuefe.repros.Simple

total     NA        RA        #nodes  time    type  #rc thread              method
(3/1425)
59063K    13406K    40025K    18345   6,174   c2    2   0x00007fdc2c28e7b0  java/lang/invoke/LambdaForm$Kind::<clinit>(()V) 

+StressRecompile:

highest peak during compilation is ~112 MB, same method, sameish node count.

./images/jdk/bin/java -XX:CompileCommand='collectmemstat,*.*' -XX:+StressRecompilation -Xcomp -Xbatch -cp $REPROS_JAR de.stuefe.repros.Simple

total     NA        RA        #nodes  time    type  #rc thread              method
(16/1434)
112M      13469K    94987K    18791   16,451  c2    2   0x00007f790428e7b0  java/lang/invoke/LambdaForm$Kind::<clinit>(()V) 

60M -> 112M. In both cases, a large part of the memory was allocated in resource areas. Its relative size compared to the total spike size increased. We accrue a lot of memory in ResourceArea over recompilations.

The solution is to wrap the Compile instantiation into a resource mark. Now we are at 61 MB, which is almost baseline:

total     NA        RA        #nodes  time    type  #rc thread              method
(3/1430)
61203K    13469K    40791K    18791   17,013  c2    2   0x00007fdf7428e7b0  java/lang/invoke/LambdaForm$Kind::<clinit>(()V) 

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Issue

  • JDK-8317987: C2 recompilations cause high memory footprint (Bug - P4)

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Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/16161/head:pull/16161
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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/16161/head

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Checkout this PR locally:
$ git pr checkout 16161

View PR using the GUI difftool:
$ git pr show -t 16161

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Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/16161.diff

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bridgekeeper bot commented Oct 12, 2023

👋 Welcome back stuefe! 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 bot commented Oct 12, 2023

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

  • hotspot-compiler

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-compiler hotspot-compiler-dev@openjdk.org label Oct 12, 2023
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tstuefe commented Oct 12, 2023

MacOs test error unrelated.

@tstuefe tstuefe marked this pull request as ready for review October 12, 2023 12:26
@openjdk openjdk bot added the rfr Pull request is ready for review label Oct 12, 2023
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mlbridge bot commented Oct 12, 2023

Webrevs

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@adinn adinn left a comment

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The holy grail of a 1-line fix that halves related memory footprint. Nice work!

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openjdk bot commented Oct 12, 2023

@tstuefe 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:

8317987: C2 recompilations cause high memory footprint

Reviewed-by: adinn, kvn

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 7 new commits pushed to the master branch:

  • c1f698d: 8317956: Make jdk.internal.util.Architecture current architecture final
  • 9355431: 8316426: Optimization for HexFormat.formatHex
  • 32ccf01: 8317772: NMT: Make peak values available in release builds
  • 4c79e7d: 8170817: G1: Returning MinTLABSize from unsafe_max_tlab_alloc causes TLAB flapping
  • 7633a76: 8317998: Temporarily disable malformed control flow assert to reduce noise in testing
  • 00ef9f9: 8316947: Write a test to check textArea triggers MouseEntered/MouseExited events properly
  • 77dc891: 8317963: Serial: Remove unused GenerationIsInReservedClosure

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
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.

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@openjdk openjdk bot added the ready Pull request is ready to be integrated label Oct 12, 2023
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tstuefe commented Oct 12, 2023

The holy grail of a 1-line fix that halves related memory footprint. Nice work!

Yes, sometimes one still finds a free lunch :)

Thanks for the review.

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Nice. We added a lot of C2 recompilation cases for the past few years so it become noticeable.
The main ResourceMark for all JIT compilers is located in CompileBroker::invoke_compiler_on_method(): compileBroker.cpp#L2141

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tstuefe commented Oct 13, 2023

Thanks @vnkozlov and @adinn!

/integrate

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openjdk bot commented Oct 13, 2023

Going to push as commit c88b387.
Since your change was applied there have been 17 commits pushed to the master branch:

  • 993951b: 8316464: 3 sun/tools tests ignore VM flags
  • 17535c3: 8317818: Combinatorial explosion during 'this' escape analysis
  • 61ce739: 8315484: java/awt/dnd/RejectDragDropActionTest.java timed out
  • 77fa44f: 8317847: Typo in API documentation of class JPopupMenu
  • 0983b54: 8318038: ProblemList runtime/CompressedOops/CompressedClassPointers.java on two platforms
  • 64ee3c9: 8317266: Move nmethod::check_all_dependencies to codeCache.cpp and mark it NOT_PRODUCT
  • 32ac72c: 8312522: Implementation of Foreign Function & Memory API
  • 9728e21: 8317967: Enhance test/jdk/javax/net/ssl/TLSCommon/SSLEngineTestCase.java to handle default cases
  • a8473b7: 8317336: Assertion error thrown during 'this' escape analysis
  • 16fd43c: 8316693: Simplify at-requires checkDockerSupport()
  • ... and 7 more: https://git.openjdk.org/jdk/compare/d95b548c78d2c504ccc3044f434f83e5c8237b0e...master

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot added the integrated Pull request has been integrated label Oct 13, 2023
@openjdk openjdk bot closed this Oct 13, 2023
@openjdk openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Oct 13, 2023
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openjdk bot commented Oct 13, 2023

@tstuefe Pushed as commit c88b387.

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

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