Reduce size of j.t.f.DateTimePrintContext::adjust #26633

wenshao · 2025-08-05T01:23:17Z

By adding the JVM startup parameters -XX:+UnlockDiagnosticVMOptions -XX:+PrintInlining and analyzing the printed log information, and found that the code size of the j.t.f.DateTimePrintContext::adjust method is 382, which is greater than 325, causing inlining failure.

@ 7   java.time.format.DateTimePrintContext::adjust (382 bytes)   failed to inline: hot method too big

By splitting the code into common/uncommon, and moving the uncommon code into adjust0, the adjust method is kept small and can be inlined by the C2 optimizer.

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bridgekeeper · 2025-08-05T01:24:24Z

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openjdk · 2025-08-05T01:25:54Z

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openjdk · 2025-08-05T01:26:25Z

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

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vy · 2025-08-05T08:51:23Z

Would you mind sharing the details about the performance improvement you observed, please? On which platforms? Using which benchmarks? (Any in test/micro/org/openjdk/bench/java/time/format?)

wenshao · 2025-08-05T16:43:06Z

By running DateTimeFormatterBench, we can see that the current proposal can improve performance by about 5% in multiple scenarios. The detailed data is as follows

1. Running performance test scripts

# before
git checkout 158e59ab9184127089f9693ce256001f64b5945c
make test TEST="micro:java.time.format.DateTimeFormatterBench"

# after
git checkout 0278bba135bed6e99a9e9f99cb656275c27f8465
make test TEST="micro:java.time.format.DateTimeFormatterBench"

2. Performance results in multiple architectures

2.1. MacBook M1 Pro (aarch64)

-# before
-Benchmark                                                   (pattern)   Mode  Cnt   Score   Error   Units
-DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  15.053 ± 0.281  ops/ms
-DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15  10.664 ± 0.119  ops/ms
-DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15   8.994 ± 0.579  ops/ms
-DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   6.943 ± 0.370  ops/ms
-DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  22.938 ± 0.056  ops/ms
-DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15  15.882 ± 0.144  ops/ms
-DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15  13.302 ± 0.518  ops/ms
-DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15  10.153 ± 0.075  ops/ms

+# after
+Benchmark                                                   (pattern)   Mode  Cnt   Score   Error   Units
+DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  16.083 ± 0.178  ops/ms +6.84%
+DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15  11.548 ± 0.171  ops/ms +8.28%
+DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15   9.835 ± 0.064  ops/ms +9.35%
+DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   7.344 ± 0.308  ops/ms +5.77%
+DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  22.500 ± 0.147  ops/ms -1.90%
+DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15  16.592 ± 0.086  ops/ms +4.47%
+DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15  13.182 ± 0.829  ops/ms -0.90%
+DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15  10.127 ± 0.140  ops/ms -0.25%

2.2. aliyun_c8y (aarch64 CPU Aliyun_Yitian 710)

-# before
-Benchmark                                                   (pattern)   Mode  Cnt   Score   Error   Units
-DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15   9.916 ± 0.073  ops/ms
-DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15   7.416 ± 0.013  ops/ms
-DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15   6.248 ± 0.082  ops/ms
-DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   4.988 ± 0.042  ops/ms
-DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  13.653 ± 0.073  ops/ms
-DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15   9.435 ± 0.033  ops/ms
-DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15   7.550 ± 0.145  ops/ms
-DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   6.096 ± 0.301  ops/ms

+# after
+Benchmark                                                   (pattern)   Mode  Cnt   Score   Error   Units
+DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  10.897 ± 0.047  ops/ms +9.89%
+DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15   7.449 ± 0.086  ops/ms +0.44%
+DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15   6.979 ± 0.025  ops/ms +11.69%
+DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   4.950 ± 0.024  ops/ms -0.76%
+DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  14.206 ± 0.206  ops/ms +4.05%
+DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15   9.957 ± 0.182  ops/ms +5.53%
+DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15   7.705 ± 0.093  ops/ms +2.05%
+DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   6.222 ± 0.235  ops/ms +2.06%

2.3. OrangePi 5 (aarch64 CPU RK3588)

-# before
-Benchmark                                                   (pattern)   Mode  Cnt  Score   Error   Units
-DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  6.118 ± 0.417  ops/ms
-DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15  4.312 ± 0.202  ops/ms
-DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15  4.047 ± 0.107  ops/ms
-DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15  2.773 ± 0.204  ops/ms
-DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  9.228 ± 0.232  ops/ms
-DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15  5.640 ± 0.223  ops/ms
-DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15  5.109 ± 0.076  ops/ms
-DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15  3.407 ± 0.168  ops/ms

+# after
+Benchmark                                                   (pattern)   Mode  Cnt  Score   Error   Units
+DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  6.080 ± 0.451  ops/ms -0.62%
+DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15  4.341 ± 0.219  ops/ms +0.67%
+DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15  4.009 ± 0.207  ops/ms -0.93%
+DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15  2.928 ± 0.104  ops/ms +5.58%
+DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  9.670 ± 0.139  ops/ms +4.78%
+DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15  5.835 ± 0.234  ops/ms +3.45%
+DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15  5.149 ± 0.153  ops/ms +0.78%
+DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15  3.553 ± 0.131  ops/ms +4.28%

2.4 aliyun_c9i (x64 CPU Intel Xeon Granite Rapids)

-# before
-Benchmark                                                   (pattern)   Mode  Cnt   Score   Error   Units
-DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  15.718 ± 1.343  ops/ms
-DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15  11.758 ± 0.638  ops/ms
-DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15  10.529 ± 0.057  ops/ms
-DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   7.945 ± 0.304  ops/ms
-DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  20.441 ± 0.067  ops/ms
-DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15  13.975 ± 0.062  ops/ms
-DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15  11.721 ± 0.070  ops/ms
-DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   8.604 ± 0.073  ops/ms

+# after
+Benchmark                                                   (pattern)   Mode  Cnt   Score   Error   Units
+DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  16.745 ± 0.129  ops/ms +6.53%
+DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15  11.571 ± 1.085  ops/ms -1.52%
+DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15  10.591 ± 0.046  ops/ms +0.58%
+DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   7.899 ± 0.323  ops/ms -0.57%
+DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  20.993 ± 0.082  ops/ms +2.70%
+DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15  14.123 ± 0.094  ops/ms +1.05%
+DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15  11.781 ± 0.054  ops/ms +0.51%
+DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   8.723 ± 0.055  ops/ms +1.38%

2.5 MacBook 2019 (x64 intel i9)

-# before
-Benchmark                                                   (pattern)   Mode  Cnt   Score   Error   Units
-DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  12.393 ± 0.985  ops/ms
-DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15   9.658 ± 0.220  ops/ms
-DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15   8.321 ± 0.098  ops/ms
-DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   6.575 ± 0.073  ops/ms
-DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  18.946 ± 0.387  ops/ms
-DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15  12.156 ± 0.316  ops/ms
-DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15   9.980 ± 0.115  ops/ms
-DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   7.729 ± 0.160  ops/ms

+# after
+Benchmark                                                   (pattern)   Mode  Cnt   Score   Error   Units
+DateTimeFormatterBench.formatInstants                        HH:mm:ss  thrpt   15  13.942 ± 0.257  ops/ms +12.49%
+DateTimeFormatterBench.formatInstants                    HH:mm:ss.SSS  thrpt   15   9.882 ± 0.327  ops/ms +2.42%
+DateTimeFormatterBench.formatInstants           yyyy-MM-dd'T'HH:mm:ss  thrpt   15   9.234 ± 0.240  ops/ms +10.97%
+DateTimeFormatterBench.formatInstants       yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   6.594 ± 0.074  ops/ms +2.89%
+DateTimeFormatterBench.formatZonedDateTime                   HH:mm:ss  thrpt   15  19.482 ± 0.385  ops/ms +2.82%
+DateTimeFormatterBench.formatZonedDateTime               HH:mm:ss.SSS  thrpt   15  12.917 ± 0.244  ops/ms +6.26%
+DateTimeFormatterBench.formatZonedDateTime      yyyy-MM-dd'T'HH:mm:ss  thrpt   15  10.196 ± 0.142  ops/ms +2.16%
+DateTimeFormatterBench.formatZonedDateTime  yyyy-MM-dd'T'HH:mm:ss.SSS  thrpt   15   7.793 ± 0.136  ops/ms +8.28%

jodastephen · 2025-08-06T09:20:30Z

src/java.base/share/classes/java/time/format/DateTimePrintContext.java

@@ -149,6 +149,12 @@ private static TemporalAccessor adjust(final TemporalAccessor temporal, DateTime
                Chronology chrono = Objects.requireNonNullElse(effectiveChrono, IsoChronology.INSTANCE);
                return chrono.zonedDateTime(Instant.from(temporal), overrideZone);
            }
+        }


Have you tested the split at different locations? I would expect line 143 or line 130 to perform best. There may be a case for splitting multiple times. You will also need a comment to indicate why the method is split.

In theory, the smaller the method, the greater the opportunity for performance improvement, but in DateTimeFormatterWithPaddingBench and DateTimeFormatterBench, the improvement is the same.

wenshao · 2025-08-06T09:26:21Z

Run the test script

make test TEST="micro:java.time.format.DateTimeFormatterWithPaddingBench"

Test results on aliyun_c9i (x64 CPU Intel Xeon Granite Rapids)

-# before
-Benchmark                                                       Mode  Cnt      Score     Error   Units
-DateTimeFormatterWithPaddingBench.formatWithPadding            thrpt   15  11823.795 ± 221.488  ops/ms
-DateTimeFormatterWithPaddingBench.formatWithPaddingLengthOne   thrpt   15  34634.499 ±  91.144  ops/ms
-DateTimeFormatterWithPaddingBench.formatWithPaddingLengthZero  thrpt   15  39070.959 ± 198.192  ops/ms

+# after
+Benchmark                                                       Mode  Cnt      Score     Error   Units
+DateTimeFormatterWithPaddingBench.formatWithPadding            thrpt   15  12257.729 ±  49.449  ops/ms +3.67%
+DateTimeFormatterWithPaddingBench.formatWithPaddingLengthOne   thrpt   15  37689.494 ± 117.526  ops/ms +8.82%
+DateTimeFormatterWithPaddingBench.formatWithPaddingLengthZero  thrpt   15  43628.181 ± 493.395  ops/ms +11.66%

In DateTimeFormatterWithPaddingBench, I found that this proposal improved performance even more.

This is because DateTimeFormatter is statically defined as final, and DateTimeFormatter::getChronology and DateTimeFormatter::getZone used in the adjust method are final fields. This eliminates dead code branches during inlining by the C2 optimizer.

The following code is the formatter definition in DateTimeFormatterWithPaddingBench. The modifiers of the fields FORMATTER_WITH_PADDING/FORMATTER_WITH_PADDING_ZERO/FORMATTER_WITH_PADDING_ONE are static final.

public class DateTimeFormatterWithPaddingBench {

    private static final DateTimeFormatter FORMATTER_WITH_PADDING = new DateTimeFormatterBuilder()
            .appendLiteral("Date:")
            .padNext(20, ' ')
            .append(DateTimeFormatter.ISO_DATE)
            .toFormatter();

    private static final DateTimeFormatter FORMATTER_WITH_PADDING_ZERO = new DateTimeFormatterBuilder()
            .appendLiteral("Year:")
            .padNext(4)
            .appendValue(ChronoField.YEAR)
            .toFormatter();

    private static final DateTimeFormatter FORMATTER_WITH_PADDING_ONE = new DateTimeFormatterBuilder()
            .appendLiteral("Year:")
            .padNext(5)
            .appendValue(ChronoField.YEAR)
            .toFormatter();

In the DateTimeFormatter related code, the modifiers of the chrono/zone fields are also final

final class DateTimeFormatter {
	private final Chronology chrono;
	private final ZoneId zone;

    public Chronology getChronology() {
        return chrono;
    }

    public ZoneId getZone() {
        return zone;
    }
}

The following code in the DateTimePrintContext::adjust method uses chrono and zone. When adjust can be inlined, dead code branches can be eliminated to improve performance.

final class DateTimePrintContext {
    private static TemporalAccessor adjust(final TemporalAccessor temporal, DateTimeFormatter formatter) {
        Chronology overrideChrono = formatter.getChronology();
        ZoneId overrideZone = formatter.getZone();
        if (overrideChrono == null && overrideZone == null) {
            return temporal;
        }
        // ....
    }
}

Separate exception handling into two separate methods to make codeSiz…

0278bba

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Reduce size of j.t.f.DateTimePrintContext::adjust #26633

Reduce size of j.t.f.DateTimePrintContext::adjust #26633

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wenshao commented Aug 5, 2025

1. Running performance test scripts

2. Performance results in multiple architectures

2.1. MacBook M1 Pro (aarch64)

2.2. aliyun_c8y (aarch64 CPU Aliyun_Yitian 710)

2.3. OrangePi 5 (aarch64 CPU RK3588)

2.4 aliyun_c9i (x64 CPU Intel Xeon Granite Rapids)

2.5 MacBook 2019 (x64 intel i9)

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