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8273684: Replace usages of java.util.Stack with ArrayDeque #5294

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turbanoff
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@turbanoff turbanoff commented Aug 29, 2021

Usage of thread-safe collection Stack is unnecessary. It's recommended to use ArrayDequeue if a thread-safe implementation is not needed.


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  • JDK-8273684: Replace usages of java.util.Stack with ArrayDeque

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@bridgekeeper bridgekeeper bot commented Aug 29, 2021

👋 Welcome back turbanoff! 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 Aug 29, 2021

@turbanoff The following labels will be automatically applied to this pull request:

  • 2d
  • serviceability
  • sound
  • swing

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.

@openjdk openjdk bot added 2d serviceability swing sound labels Aug 29, 2021
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@mrserb mrserb commented Sep 10, 2021

Looks fine

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@mrserb mrserb commented Sep 10, 2021

Or maybe not, did you check that the order of pushing and the order of iteration for the stack and ArrayDeque are the same? I am not sure about it.

Replace one usage of ArrayList instead of ArrayDeque to preserve order of array elements as it was in original code
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@turbanoff turbanoff commented Sep 10, 2021

Yeah. You are right! TIL that order of iteration is different in ArrayDequeu vs Stack: Stack.push() adds to the "end of stack" (it just calls Vector.add()), while ArrayDeque.push adds "first element"
Luckily for us there was only one place which depend on this. It's small method javax.swing.text.html.HTMLDocument.HTMLReader#getPathTo. I've changed method to use ArrayList instead.

@turbanoff turbanoff changed the title [PATCH] Stack usages can be replaced with ArrayDequeue [PATCH] Stack usages can be replaced with ArrayDequeue or ArrayList Sep 10, 2021
@turbanoff turbanoff changed the title [PATCH] Stack usages can be replaced with ArrayDequeue or ArrayList 8273684: Unnecessary Stack usage Sep 13, 2021
@openjdk openjdk bot added the rfr label Sep 13, 2021
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@mlbridge mlbridge bot commented Sep 13, 2021

Webrevs

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@mlbridge mlbridge bot commented Sep 14, 2021

Mailing list message from Bernd Eckenfels on serviceability-dev:

Maybe better use addFirst(), for example in CommandProcessor there is a comment that order matters (did not check it more closely), so it?s probably best to not reverse orders in any place? The Dequeue Javadoc lists addFirst as the aproperiate stack#push replacement.

Gruss
Bernd
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http://bernd.eckenfels.net
________________________________
Von: serviceability-dev <serviceability-dev-retn at openjdk.java.net> im Auftrag von Andrey Turbanov <github.com+741251+turbanoff at openjdk.java.net>
Gesendet: Monday, September 13, 2021 9:29:26 PM
An: client-libs-dev at openjdk.java.net <client-libs-dev at openjdk.java.net>; serviceability-dev at openjdk.java.net <serviceability-dev at openjdk.java.net>
Betreff: Re: RFR: 8273684: Unnecessary Stack usage

On Sun, 29 Aug 2021 21:14:19 GMT, Andrey Turbanov <github.com+741251+turbanoff at openjdk.org> wrote:

Usage of thread-safe collection Stack is unnecessary. It's recommended to use ArrayDequeue if a thread-safe implementation is not needed.

Yeah. You are right! TIL that order of iteration is different in ArrayDequeu vs Stack: Stack.push() adds to the "end of stack" (it just calls Vector.add()), while ArrayDeque.push adds "first element"
Luckily for us there was only one place which depend on this. It's small method `javax.swing.text.html.HTMLDocument.HTMLReader#getPathTo`. I've changed method to use ArrayList instead.

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PR: https://git.openjdk.java.net/jdk/pull/5294
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@turbanoff turbanoff commented Sep 14, 2021

Maybe better use addFirst(), for example in CommandProcessor there is a comment that order matters (did not check it more closely), so it?s probably best to not reverse orders in any place?

In all other places (except HTMLReader), iteration order don't matter. Stack only accessed via classic well known stack operations: push, pop, peek. This methods work in the same way in ArrayDeque. So I think replacing with addFirst isn't necessary.

@@ -985,7 +985,7 @@ public void doit(Tokens t) {
Iterator i = agent.getTypeDataBase().getTypes();
// Make sure the types are emitted in an order than can be read back in
HashSet<String> emitted = new HashSet<>();
Stack<Type> pending = new Stack<>();
ArrayDeque<Type> pending = new ArrayDeque<>();
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Have you run the clhsdb vmstructsdump command to make sure the ordering hasn't changed?

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There is something wrong with the version of jhsdb you are running. It appears to be an old version, not the latest. You should not be seeing the following warning. The code that produces it is not even present in the latest jdk.
Warning: Nashorn engine is planned to be removed from a future JDK release

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I wondered about this too. Perhaps this messages coming from the target JDK which I'm attached too?
I attached to my IntelliJ IDEA process. It uses JDK 11.

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SA doesn't doesn't run any code on the target.

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I wonder if you are exporting CLASSPATH and that is causing jhsdb to pick up the wrong SA implementation.

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Rechecked again.
Now without involving IDEA. Just started small java program and then attached.
Then checkouted revision before my commits (a9188f2) and rebuild and repeated.
изображение

with_fixes_java_vmstructsdump.txt
without_fixes_java_vmstructsdump.txt

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Ok, looks good. You can consider the SA changes reviewed.

@turbanoff turbanoff changed the title 8273684: Unnecessary Stack usage 8273684: Replace usages of java.util.Stack with ArrayDeque Sep 15, 2021
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@turbanoff 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:

8273684: Replace usages of java.util.Stack with ArrayDeque

Reviewed-by: cjplummer, serb

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 235 new commits pushed to the master branch:

  • 2a2e919: 8273685: Remove jtreg tag manual=yesno for java/awt/Graphics/LCDTextAndGraphicsState.java & show test instruction
  • 8302061: 8273774: CDSPluginTest should only expect classes_nocoops.jsa exists on supported 64-bit platforms
  • 2f8c221: 8273681: Add Vector API vs Arrays.mismatch intrinsic benchmark
  • 17f7a45: 8273913: Problem list some headful client jtreg tests that fail on macOS 12
  • 27d747a: 8273877: os::unsetenv unused
  • 35f6f1d: 8273808: Cleanup AddFontsToX11FontPath
  • 1890d85: 8273872: ZGC: Explicitly use 2M large pages
  • 54b4567: 8273880: Zero: Print warnings when unsupported intrinsics are enabled
  • e07ab82: 8273408: java.lang.AssertionError: typeSig ERROR on generated class property of record
  • 8c022e2: 8270434: JDI+UT: Unexpected event in JDI tests
  • ... and 225 more: https://git.openjdk.java.net/jdk/compare/a9188f237ec23d4ca2a172e9a7897cb6e2b69857...master

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@openjdk openjdk bot added the ready label Sep 15, 2021
mrserb
mrserb approved these changes Sep 17, 2021
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@turbanoff turbanoff commented Sep 17, 2021

/integrate

@openjdk openjdk bot added the sponsor label Sep 17, 2021
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@openjdk openjdk bot commented Sep 17, 2021

@turbanoff
Your change (at version e39a52f) is now ready to be sponsored by a Committer.

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@mrserb mrserb commented Sep 22, 2021

/sponsor

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@openjdk openjdk bot commented Sep 22, 2021

Going to push as commit cbe57e8.
Since your change was applied there have been 277 commits pushed to the master branch:

  • a72c8aa: 8273921: Refactor NSK/JDI tests to create thread using factory
  • 161fdb4: 8273935: (zipfs) Files.getFileAttributeView() throws UOE instead of returning null when view not supported
  • 0fc47e9: 8266666: Implementation for snippets
  • 6d91a3e: 8269039: Disable SHA-1 Signed JARs
  • 42d5d2a: 8274056: JavaAccessibilityUtilities leaks JNI objects
  • 57df0db: 8270873: JFR: Catch DirectoryIteratorException when scanning for .jfr files
  • 111d5e1: 8273915: Create 'nosafepoint' rank
  • 7acec3f: 8236505: Mark jdk/editpad/EditPadTest.java as @headful
  • afd218d: 8274053: [BACKOUT] JDK-8270842: G1: Only young regions need to redirty outside references in remset.
  • a5108a6: 8273646: Add openssl from path variable also in to Default System Openssl Path in OpensslArtifactFetcher
  • ... and 267 more: https://git.openjdk.java.net/jdk/compare/a9188f237ec23d4ca2a172e9a7897cb6e2b69857...master

Your commit was automatically rebased without conflicts.

@openjdk openjdk bot closed this Sep 22, 2021
@openjdk openjdk bot added integrated and removed ready rfr sponsor labels Sep 22, 2021
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@openjdk openjdk bot commented Sep 22, 2021

@mrserb @turbanoff Pushed as commit cbe57e8.

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

@turbanoff turbanoff deleted the avoid_unnecessary_stack_usage branch Oct 4, 2021
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