8358426: Improve lazy computation in Locale by justin-curtis-lu · Pull Request #25646 · openjdk/jdk

justin-curtis-lu · 2025-06-04T21:20:46Z

Please review this PR which improves occurrences of lazy computation in Locale and BaseLocale.

Existing lazy initialization strategies such as CHM, static nested class, and local inner class are replaced with Stable Values.

Lambda usage is intentionally avoided in this change during Locale creation and in static fields due to potential startup performance degradation as noted by JDK-8331932.

Rather than convert iso3166CodesMap to a Stable Map, each ISO 3166 resource is represented as a SV. Also, I did not think it was necessary to maintain a SV for both the array and set of ISO3166-1 alpha-2 codes.

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Issue

JDK-8358426: Improve lazy computation in Locale (Bug - P4)

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Chen Liang (@liach - Reviewer) Review applies to b679594c
Naoto Sato (@naotoj - Reviewer)

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bridgekeeper · 2025-06-04T21:21:31Z

👋 Welcome back jlu! 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 · 2025-06-04T21:22:15Z

@justin-curtis-lu 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:

8358426: Improve lazy computation in Locale

Reviewed-by: naoto, liach

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 42 new commits pushed to the master branch:

026975a: 8358721: Update JCov for class file version 70
8adb052: 8341778: Some javac tests ignore the result of JavacTask::call
9658cec: 8358685: [TEST] AOTLoggingTag.java failed with missing log message
... and 39 more: https://git.openjdk.org/jdk/compare/fd0ab043677d103628afde628e3e75e23fb518b2...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 · 2025-06-04T21:22:46Z

@justin-curtis-lu The following labels will be automatically applied to this pull request:

core-libs
i18n

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.

mlbridge · 2025-06-04T21:26:03Z

Webrevs

01: Full - Incremental (e6f3d0de)
00: Full (b679594c)

liach

Looks correct. Note we have a separate effort #25040 to avoid anonymous supplier classes, don't know if @minborg wishes locale to migrate to that one directly or remain on the more high-level SV.

turbanoff · 2025-06-05T08:37:38Z

src/java.base/share/classes/java/util/Locale.java

    private static volatile Locale defaultFormatLocale;

-    private transient volatile String languageTag;
+    private transient final Supplier<String> languageTag =


let's use blessed modifiers order

Suggested change

private transient final Supplier<String> languageTag =

private final transient Supplier<String> languageTag =

minborg · 2025-06-05T10:55:15Z

Looks good! As @liach mentioned, there is an even better way coming, but I think it's good to do this update anyway. Here is a similar one that I am working on: #25630

So, once we have stable field updaters, it will be almost trivial to update the code in this PR.

jdlib · 2025-06-05T11:50:01Z

src/java.base/share/classes/java/util/Locale.java

-        System.arraycopy(isoCountries, 0, result, 0, isoCountries.length);
-        return result;
+        String[] countries = ISO_3166_1_ALPHA2.get();
+        return Arrays.copyOf(countries, countries.length);


what about return ISO_3166_1_ALPHA2.get().clone();

clone is more concise, but I think I prefer the explicitness of copyOf here.

jdlib · 2025-06-05T11:55:31Z

src/java.base/share/classes/java/util/Locale.java

+                public Set<String> get() {
+                    return Set.of(LocaleISOData.ISO3166_3);
+                }
+            });


What about moving these four stable suppliers and getISO2Table to LocaleISOData to shrink size of Locale.java?

I like this suggestion, we can also move getISO3Code in addition to those you mentioned, and have all ISO resources and methods come from LocaleISOData. @naotoj, would you be in favor of this?

I agree, that would be more straightforward. Thanks for the suggestion!

… order for languageTag

naotoj

LGTM

j3graham · 2025-06-07T17:36:40Z

src/java.base/share/classes/java/util/Locale.java

    public static Set<String> getISOCountries(IsoCountryCode type) {
        Objects.requireNonNull(type);
-        return IsoCountryCode.retrieveISOCountryCodes(type);
+        return switch (type) {


The body of this method could also be moved to a method in LocaleISOData

I think it's OK as is, don't want to force re-approvals. Currently it is consistent with the other ISO related methods in Locale, which grab the ISO resources from LocaleISOData but handle some logic on their own as well.

justin-curtis-lu · 2025-06-09T20:49:15Z

Thank you for the reviews!
/integrate

openjdk · 2025-06-09T20:49:33Z

Going to push as commit cd9b1bc.
Since your change was applied there have been 56 commits pushed to the master branch:

fcb68ea: 8358626: Emit UTF-8 CLDR resources
eb256de: 8358326: Use oopFactory array allocation
156187a: 8356978: Convert unicode sequences in Java source code to UTF-8
... and 53 more: https://git.openjdk.org/jdk/compare/fd0ab043677d103628afde628e3e75e23fb518b2...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-06-09T20:49:40Z

@justin-curtis-lu Pushed as commit cd9b1bc.

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

init

b679594

openjdk bot changed the title ~~JDK-8358426: Improve lazy computation in Locale~~ 8358426: Improve lazy computation in Locale Jun 4, 2025

openjdk bot added the rfr Pull request is ready for review label Jun 4, 2025

openjdk bot added core-libs core-libs-dev@openjdk.org i18n i18n-dev@openjdk.org labels Jun 4, 2025

liach approved these changes Jun 5, 2025

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graalvmbot mentioned this pull request Jun 5, 2025

[JDK-8358675] Adapt JDK-8358426: Improve lazy computation in Locale oracle/graal#11341

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jdlib reviewed Jun 5, 2025

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review - Moving all ISO resources to LocaleISOData & blessed modifier…

e6f3d0d

… order for languageTag

openjdk bot removed the ready Pull request is ready to be integrated label Jun 5, 2025

naotoj approved these changes Jun 6, 2025

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openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Jun 9, 2025

graalvmbot mentioned this pull request Jun 18, 2025

[GR-65949] Update labsjdk to 26+2-jvmci-b01 oracle/graal#11431

Merged

	private transient final Supplier<String> languageTag =
	private final transient Supplier<String> languageTag =

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