8372460: Use EnumMap instead of HashMap for DateTimeFormatter parsing to improve performance

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

@@ -544,6 +544,12 @@ public final class DateTimeFormatter {
      */
     private final ZoneId zone;
 
+    /**
+     * Flag indicating whether this formatter only uses ChronoField instances.
+     * This is used to optimize the storage of parsed field values in the Parsed class.
+     */
+    final boolean onlyChronoField;
+
     //-----------------------------------------------------------------------
     /**
      * Creates a formatter using the specified pattern.
@@ -1474,18 +1480,20 @@ public static final TemporalQuery<Boolean> parsedLeapSecond() {
      * @param resolverFields  the fields to use during resolving, null for all fields
      * @param chrono  the chronology to use, null for no override
      * @param zone  the zone to use, null for no override
+     * @param onlyChronoField  flag indicating whether this formatter only uses ChronoField instances
      */
     DateTimeFormatter(CompositePrinterParser printerParser,
             Locale locale, DecimalStyle decimalStyle,
             ResolverStyle resolverStyle, Set<TemporalField> resolverFields,
-            Chronology chrono, ZoneId zone) {
+            Chronology chrono, ZoneId zone, boolean onlyChronoField) {
         this.printerParser = Objects.requireNonNull(printerParser, "printerParser");
         this.resolverFields = resolverFields;
         this.locale = Objects.requireNonNull(locale, "locale");
         this.decimalStyle = Objects.requireNonNull(decimalStyle, "decimalStyle");
         this.resolverStyle = Objects.requireNonNull(resolverStyle, "resolverStyle");
         this.chrono = chrono;
         this.zone = zone;
+        this.onlyChronoField = onlyChronoField;
     }
 
     //-----------------------------------------------------------------------
@@ -1523,7 +1531,7 @@ public DateTimeFormatter withLocale(Locale locale) {
         if (this.locale.equals(locale)) {
             return this;
         }
-        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone);
+        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone, onlyChronoField);
     }
 
     /**
@@ -1569,7 +1577,7 @@ public DateTimeFormatter localizedBy(Locale locale) {
                 Objects.equals(z, zone)) {
             return this;
         } else {
-            return new DateTimeFormatter(printerParser, locale, ds, resolverStyle, resolverFields, c, z);
+            return new DateTimeFormatter(printerParser, locale, ds, resolverStyle, resolverFields, c, z, onlyChronoField);
         }
     }
 
@@ -1595,7 +1603,7 @@ public DateTimeFormatter withDecimalStyle(DecimalStyle decimalStyle) {
         if (this.decimalStyle.equals(decimalStyle)) {
             return this;
         }
-        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone);
+        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone, onlyChronoField);
     }
 
     //-----------------------------------------------------------------------
@@ -1649,7 +1657,7 @@ public DateTimeFormatter withChronology(Chronology chrono) {
         if (Objects.equals(this.chrono, chrono)) {
             return this;
         }
-        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone);
+        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone, onlyChronoField);
     }
 
     //-----------------------------------------------------------------------
@@ -1706,7 +1714,7 @@ public DateTimeFormatter withZone(ZoneId zone) {
         if (Objects.equals(this.zone, zone)) {
             return this;
         }
-        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone);
+        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone, onlyChronoField);
     }
 
     //-----------------------------------------------------------------------
@@ -1748,7 +1756,7 @@ public DateTimeFormatter withResolverStyle(ResolverStyle resolverStyle) {
         if (Objects.equals(this.resolverStyle, resolverStyle)) {
             return this;
         }
-        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone);
+        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone, onlyChronoField);
     }
 
     //-----------------------------------------------------------------------
@@ -1814,7 +1822,7 @@ public DateTimeFormatter withResolverFields(TemporalField... resolverFields) {
         if (Objects.equals(this.resolverFields, fields)) {
             return this;
         }
-        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, fields, chrono, zone);
+        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, fields, chrono, zone, onlyChronoField);
     }
 
     /**
@@ -1863,7 +1871,7 @@ public DateTimeFormatter withResolverFields(Set<TemporalField> resolverFields) {
         if (resolverFields != null) {
             resolverFields = Collections.unmodifiableSet(new HashSet<>(resolverFields));
         }
-        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone);
+        return new DateTimeFormatter(printerParser, locale, decimalStyle, resolverStyle, resolverFields, chrono, zone, onlyChronoField);
     }
 
     //-----------------------------------------------------------------------

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

@@ -200,6 +200,12 @@ public final class DateTimeFormatterBuilder {
      */
     private int valueParserIndex = -1;
 
+    /**
+     * Flag indicating whether this builder only uses ChronoField instances.
+     * This is used to optimize the storage of parsed field values in the Parsed class.
+     */
+    private boolean onlyChronoField = true;
+
     /**
      * Gets the formatting pattern for date and time styles for a locale and chronology.
      * The locale and chronology are used to lookup the locale specific format
@@ -2371,11 +2377,35 @@ private int appendInternal(DateTimePrinterParser pp) {
             active.padNextWidth = 0;
             active.padNextChar = 0;
         }
+
+        // Update the onlyChronoField flag if the printer/parser uses non-ChronoField instances
+        checkField(pp);
         active.printerParsers.add(pp);
         active.valueParserIndex = -1;
         return active.printerParsers.size() - 1;
     }
 
+    /**
+     * Update the onlyChronoField flag if the printer/parser uses non-ChronoField instances
+     * @param pp the printer-parser
+     */
+    private void checkField(DateTimePrinterParser pp) {
+        TemporalField field;
+        if (pp instanceof NumberPrinterParser npp) {
+            field = npp.field;
+        } else if (pp instanceof TextPrinterParser tpp) {
+            field = tpp.field;
+        } else if (pp instanceof DefaultValueParser dvp) {
+            field = dvp.field;
+        } else {
+            return;
+        }
+
+        if (!(field instanceof ChronoField)) {
+            active.onlyChronoField = false;
+        }
+    }
+
     //-----------------------------------------------------------------------
     /**
      * Completes this builder by creating the {@code DateTimeFormatter}
@@ -2443,7 +2473,7 @@ private DateTimeFormatter toFormatter(Locale locale, ResolverStyle resolverStyle
         }
         CompositePrinterParser pp = new CompositePrinterParser(printerParsers, false);
         return new DateTimeFormatter(pp, locale, DecimalStyle.STANDARD,
-                resolverStyle, null, chrono, null);
+                resolverStyle, null, chrono, null, onlyChronoField);
     }
 
     //-----------------------------------------------------------------------

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -120,7 +120,7 @@ final class DateTimeParseContext {
     DateTimeParseContext(DateTimeFormatter formatter) {
         super();
         this.formatter = formatter;
-        parsed.add(new Parsed());
+        parsed.add(new Parsed(formatter.onlyChronoField));
     }
 
     /**

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

@@ -1,5 +1,6 @@
 /*
- * Copyright (c) 2012, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2025, Alibaba Group Holding Limited. All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -98,6 +99,7 @@
 import java.time.temporal.TemporalQueries;
 import java.time.temporal.TemporalQuery;
 import java.time.temporal.UnsupportedTemporalTypeException;
+import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
@@ -128,7 +130,7 @@ final class Parsed implements TemporalAccessor {
     /**
      * The parsed fields.
      */
-    final Map<TemporalField, Long> fieldValues = new HashMap<>();
+    final Map<TemporalField, Long> fieldValues;
     /**
      * The parsed zone.
      */
@@ -169,15 +171,20 @@ final class Parsed implements TemporalAccessor {
     /**
      * Creates an instance.
      */
-    Parsed() {
+    @SuppressWarnings("unchecked")
+    Parsed(boolean onlyChronoField) {
+        // Create the EnumMap with raw types and cast it appropriately
+        // This is safe because ChronoField implements TemporalField
+        fieldValues = onlyChronoField ? (Map<TemporalField, Long>) (Map) new EnumMap<>(ChronoField.class)
+                                      : new HashMap<>();
     }
 
     /**
      * Creates a copy.
      */
     Parsed copy() {
         // only copy fields used in parsing stage
-        Parsed cloned = new Parsed();
+        Parsed cloned = new Parsed(fieldValues instanceof EnumMap);
         cloned.fieldValues.putAll(this.fieldValues);
         cloned.zone = this.zone;
         cloned.zoneNameType = this.zoneNameType;

test/micro/org/openjdk/bench/java/time/format/DateTimeFormatterParse.java

@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2025, Alibaba Group Holding Limited. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.openjdk.bench.java.time.format;
+
+import java.time.Duration;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.LocalTime;
+import java.time.OffsetDateTime;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+import java.time.temporal.ChronoUnit;
+
+import java.util.Locale;
+import java.util.Random;
+import java.util.TimeZone;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+
+@BenchmarkMode(Mode.Throughput)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Warmup(iterations = 5, time = 1)
+@Measurement(iterations = 5, time = 1)
+@Fork(3)
+@State(Scope.Thread)
+public class DateTimeFormatterParse {
+    static final DateTimeFormatter formatterLocalTime = DateTimeFormatter.ofPattern("HH:mm:ss");
+    static final DateTimeFormatter formatterLocalTimeWithNano = DateTimeFormatter.ofPattern("HH:mm:ss.SSS");
+    static final DateTimeFormatter formatterLocalDate = DateTimeFormatter.ofPattern("yyyy-MM-dd");
+    static final DateTimeFormatter formatterLocalDateTime = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss");
+    static final DateTimeFormatter formatterLocalDateTimeWithNano = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSS");
+    static final DateTimeFormatter formatterOffsetDateTime = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSSSSZZZZZ");
+    static final DateTimeFormatter formatterZonedDateTime = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSSSSZZZZZ'['VV']'");
+
+    static final String STR_LOCALTIME = "21:11:48";
+    static final String STR_LOCALTIME_WITH_NANO = "21:11:48.456";
+    static final String STR_LOCALDATE = "2024-08-01";
+    static final String STR_LOCALDATETIME = "2024-08-01T21:11:48";
+    static final String STR_LOCALDATETIME_WITH_NANO = "2024-08-01T21:11:48.456";
+    static final String STR_INSTANT = "2024-08-12T03:25:54.980339Z";
+    static final String STR_OFFSETDATETIME = "2024-08-12T11:50:46.731509+08:00";
+    static final String STR_ZONEDDATETIME = "2024-08-12T11:50:46.731509+08:00[Asia/Shanghai]";
+
+    @Benchmark
+    public LocalTime parseLocalTime() {
+        return LocalTime.parse(STR_LOCALTIME, formatterLocalTime);
+    }
+
+    @Benchmark
+    public LocalTime parseLocalTimeWithNano() {
+        return LocalTime.parse(STR_LOCALTIME_WITH_NANO, formatterLocalTimeWithNano);
+    }
+
+    @Benchmark
+    public LocalDate parseLocalDate() {
+        return LocalDate.parse(STR_LOCALDATE, formatterLocalDate);
+    }
+
+    @Benchmark
+    public LocalDateTime parseLocalDateTime() {
+        return LocalDateTime.parse(STR_LOCALDATETIME, formatterLocalDateTime);
+    }
+
+    @Benchmark
+    public LocalDateTime parseLocalDateTimeWithNano() {
+        return LocalDateTime.parse(STR_LOCALDATETIME_WITH_NANO, formatterLocalDateTimeWithNano);
+    }
+
+    @Benchmark
+    public OffsetDateTime parseOffsetDateTime() {
+        return OffsetDateTime.parse(STR_OFFSETDATETIME, formatterOffsetDateTime);
+    }
+
+    @Benchmark
+    public ZonedDateTime parseZonedDateTime() {
+        return ZonedDateTime.parse(STR_ZONEDDATETIME, formatterZonedDateTime);
+    }
+
+    @Benchmark
+    public Instant parseInstant() {
+        return Instant.parse(STR_INSTANT);
+    }
+}