8373566: Performance regression with java.text.MessageFormat subformat patterns by justin-curtis-lu · Pull Request #28806 · openjdk/jdk

justin-curtis-lu · 2025-12-12T21:59:52Z

This PR addresses a performance degradation when constructing a new MessageFormat that contains a subformat with a pattern that is not a predefined style. This is due to internal logic which catches an IAE specifically for subformat patterns. Perf tests for choice and number are not grouped, since performance is directly tied to subformat creation.

M1 Mac - Perf (before):

MessageFormatterBench.testSubformatChoice  thrpt   15   865.430 ±  6.766  ops/ms
MessageFormatterBench.testSubformatNumber  thrpt   15  1021.808 ± 11.413  ops/ms

M1 Mac - Perf (after):

Benchmark                                   Mode  Cnt     Score    Error   Units
MessageFormatterBench.testSubformatChoice  thrpt   15  1671.033 ± 55.012  ops/ms
MessageFormatterBench.testSubformatNumber  thrpt   15  3275.727 ± 47.370  ops/ms

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Issue

JDK-8373566: Performance regression with java.text.MessageFormat subformat patterns (Bug - P4)

Reviewers

Naoto Sato (@naotoj - Reviewer) Review applies to 8c80ce3e
Chen Liang (@liach - Reviewer)
Roger Riggs (@RogerRiggs - Reviewer)

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bridgekeeper · 2025-12-12T22:01:50Z

👋 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 · 2025-12-12T22:02:33Z

@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:

8373566: Performance regression with java.text.MessageFormat subformat patterns

Reviewed-by: liach, rriggs, naoto

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 46 new commits pushed to the master branch:

3f33eaa: 8373649: Convert simple AtomicAccess usage in ConcurrentHashTable to use Atomic
1748737: 8372988: Test runtime/Nestmates/membership/TestNestHostErrorWithMultiThread.java failed: Unexpected interrupt
317788f: 8360160: ubuntu-22-04 machine is failing client tests
... and 43 more: https://git.openjdk.org/jdk/compare/ae85d899d074c531371dece30319ace701517528...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 · 2025-12-12T22:03:27Z

@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 · 2025-12-12T22:07:05Z

Webrevs

naotoj

Looks good. Glad we fixed the performance regression, and kudos to the bug submitter

naotoj · 2025-12-12T22:30:15Z

src/java.base/share/classes/java/text/MessageFormat.java

+        UNIT;
+
+        // Returns a FormatStyle corresponding to the input text
+        // DEFAULT is the empty String, the pre-defined styles are 1-1 with their


The comment could mention that pre-defined ones are lower case ones of the enum names, but compared with the input styles ignoring cases for historical reasons

liach · 2025-12-12T22:38:56Z

src/java.base/share/classes/java/text/MessageFormat.java

+            for (int i = 2; i < styles.length; i ++) {
+                var fStyle = styles[i];
+                // case-insensitive comp for compatibility
+                if (style.compareToIgnoreCase(fStyle.toString()) == 0) {


Suggested change

if (style.compareToIgnoreCase(fStyle.toString()) == 0) {

if (style.compareToIgnoreCase(fStyle.name()) == 0) {

naotoj · 2025-12-12T23:15:57Z

src/java.base/share/classes/java/text/MessageFormat.java

+            }
+            var styles = values();
+            // Match starting at the pre-defined styles -> [SHORT:]
+            for (int i = 2; i < styles.length; i ++) {


nit: SHORT.ordinal() can be used

turbanoff · 2025-12-15T20:42:11Z

src/java.base/share/classes/java/text/MessageFormat.java

+            }
+            var styles = values();
+            // Match starting at the pre-defined styles -> [SHORT:]
+            for (int i = SHORT.ordinal(); i < styles.length; i ++) {


Suggested change

for (int i = SHORT.ordinal(); i < styles.length; i ++) {

for (int i = SHORT.ordinal(); i < styles.length; i++) {

RogerRiggs

Looks good

justin-curtis-lu · 2025-12-16T18:09:38Z

Thanks for the reviews.
/integrate

openjdk · 2025-12-16T18:11:38Z

Going to push as commit 81e3757.
Since your change was applied there have been 55 commits pushed to the master branch:

76e79db: 8371716: C2: Phi node fails Value()'s verification when speculative types clash
89e7751: 8370922: Template Framework Library: Float16 type and operations
a61394b: 8373789: No PCH release build failure after JDK-8372543
... and 52 more: https://git.openjdk.org/jdk/compare/ae85d899d074c531371dece30319ace701517528...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-12-16T18:11:54Z

@justin-curtis-lu Pushed as commit 81e3757.

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

justin-curtis-lu added 2 commits December 12, 2025 10:13

impl

79ee542

perf

702b35f

openjdk bot changed the title ~~JDK-8373566: Performance regression with java.text.MessageFormat subformat patterns~~ 8373566: Performance regression with java.text.MessageFormat subformat patterns Dec 12, 2025

openjdk bot added core-libs core-libs-dev@openjdk.org i18n i18n-dev@openjdk.org labels Dec 12, 2025

openjdk bot added the rfr Pull request is ready for review label Dec 12, 2025

pull values() into a var

8eea336

naotoj reviewed Dec 12, 2025

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liach reviewed Dec 12, 2025

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Reflect suggestions from Naoto & Chen

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naotoj reviewed Dec 12, 2025

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use SHORT.ordinal()

8c80ce3

naotoj approved these changes Dec 15, 2025

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liach approved these changes Dec 15, 2025

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turbanoff reviewed Dec 15, 2025

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spacing of increment

2fe7759

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liach approved these changes Dec 15, 2025

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RogerRiggs approved these changes Dec 16, 2025

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openjdk bot closed this Dec 16, 2025

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	if (style.compareToIgnoreCase(fStyle.toString()) == 0) {
	if (style.compareToIgnoreCase(fStyle.name()) == 0) {

	for (int i = SHORT.ordinal(); i < styles.length; i ++) {
	for (int i = SHORT.ordinal(); i < styles.length; i++) {

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