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

turbanoff · 2021-08-29T21:14:19Z

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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Issue

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

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Chris Plummer (@plummercj - Reviewer)
Sergey Bylokhov (@mrserb - Reviewer)

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$ git checkout pull/5294

Update a local copy of the PR:
$ git checkout pull/5294
$ git pull https://git.openjdk.java.net/jdk pull/5294/head

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bridgekeeper · 2021-08-29T21:15:09Z

👋 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.

openjdk · 2021-08-29T21:17:48Z

@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.

missing piece

src/java.desktop/share/classes/com/sun/media/sound/DLSSoundbank.java

src/java.desktop/share/classes/javax/swing/text/html/HTMLDocument.java

post-review

one redundant import

mrserb · 2021-09-10T04:12:30Z

Looks fine

mrserb · 2021-09-10T04:21:23Z

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

turbanoff · 2021-09-10T07:44:23Z

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.

mlbridge · 2021-09-13T19:29:21Z

Webrevs

00: Full (e39a52f4)

mlbridge · 2021-09-14T00:33:32Z

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
--
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 · 2021-09-14T07:28:32Z

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.

plummercj · 2021-09-14T17:52:03Z

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/CommandProcessor.java

@@ -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<>();


Have you run the clhsdb vmstructsdump command to make sure the ordering hasn't changed?

Checked.
Ordering is the same.

with_fixes_java_vmstructsdump.txt
without_fixes_java_vmstructsdump.txt

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

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.

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

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

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.

with_fixes_java_vmstructsdump.txt
without_fixes_java_vmstructsdump.txt

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

openjdk · 2021-09-15T18:43:13Z

@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

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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@plummercj, @mrserb) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

turbanoff · 2021-09-17T21:31:04Z

/integrate

openjdk · 2021-09-17T21:33:10Z

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

mrserb · 2021-09-22T01:25:06Z

/sponsor

openjdk · 2021-09-22T01:26:34Z

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 · 2021-09-22T01:26:49Z

@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.

[PATCH] Stack usages can be replaced with ArrayDequeue

e9bf273

openjdk bot added 2d serviceability swing sound labels Aug 29, 2021

[PATCH] Stack usages can be replaced with ArrayDequeue

2f9b1cf

missing piece

mrserb reviewed Sep 8, 2021

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src/java.desktop/share/classes/com/sun/media/sound/DLSSoundbank.java Show resolved Hide resolved

mrserb reviewed Sep 8, 2021

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src/java.desktop/share/classes/javax/swing/text/html/HTMLDocument.java Outdated Show resolved Hide resolved

turbanoff added 2 commits September 9, 2021 10:03

[PATCH] Stack usages can be replaced with ArrayDequeue

3e701c0

post-review

[PATCH] Stack usages can be replaced with ArrayDequeue

d13d231

one redundant import

[PATCH] Stack usages can be replaced with ArrayDequeue

e39a52f

Replace one usage of ArrayList instead of ArrayDeque to preserve order of array elements as it was in original code

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 changed the title ~~[PATCH] Stack usages can be replaced with ArrayDequeue or ArrayList~~ 8273684: Unnecessary Stack usage Sep 13, 2021

openjdk bot added the rfr label Sep 13, 2021

plummercj reviewed Sep 14, 2021

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plummercj approved these changes Sep 15, 2021

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

openjdk bot added the ready label Sep 15, 2021

mrserb approved these changes Sep 17, 2021

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openjdk bot added the sponsor label Sep 17, 2021

openjdk bot closed this Sep 22, 2021

openjdk bot added integrated and removed ready rfr sponsor labels Sep 22, 2021

turbanoff deleted the avoid_unnecessary_stack_usage branch October 4, 2021 10:32

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

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

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

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

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