Faster dimension deserialization on the brokers

benchmarks/src/test/java/org/apache/druid/benchmark/GroupByDeserializationBenchmark.java

@@ -0,0 +1,193 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.benchmark;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.ImmutableMap;
+import org.apache.druid.common.config.NullHandling;
+import org.apache.druid.guice.NestedDataModule;
+import org.apache.druid.jackson.AggregatorsModule;
+import org.apache.druid.java.util.common.DateTimes;
+import org.apache.druid.java.util.common.Pair;
+import org.apache.druid.java.util.common.StringUtils;
+import org.apache.druid.java.util.common.granularity.Granularities;
+import org.apache.druid.query.QueryRunnerTestHelper;
+import org.apache.druid.query.aggregation.SerializablePairLongString;
+import org.apache.druid.query.aggregation.post.ConstantPostAggregator;
+import org.apache.druid.query.dimension.DefaultDimensionSpec;
+import org.apache.druid.query.dimension.DimensionSpec;
+import org.apache.druid.query.groupby.GroupByQuery;
+import org.apache.druid.query.groupby.GroupByQueryConfig;
+import org.apache.druid.query.groupby.GroupByQueryQueryToolChest;
+import org.apache.druid.query.groupby.ResultRow;
+import org.apache.druid.segment.TestHelper;
+import org.apache.druid.segment.column.ColumnType;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Level;
+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;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+@State(Scope.Benchmark)
+@Fork(value = 1)
+@Warmup(iterations = 3)
+@Measurement(iterations = 5)
+public class GroupByDeserializationBenchmark
+{
+
+  static {
+    NullHandling.initializeForTests();
+    NestedDataModule.registerHandlersAndSerde();
+    AggregatorsModule.registerComplexMetricsAndSerde();
+  }
+
+  @Param({"100", "1000"})
+  private int numDimensions;
+
+  @Param({"0", "0.25", "0.5", "0.75", "0.85", "0.95", "0.99", "1.0"})
+  private double primitiveToComplexDimensionRatio;
+
+  @Param({"json", "serializablePairLongString"})
+  private String complexDimensionType;
+
+  @Param({"true", "false"})
+  private boolean backwardCompatibility;
+
+  private GroupByQuery sqlQuery;
+  private String serializedRow;
+  private GroupByQueryQueryToolChest groupByQueryQueryToolChest;
+  private ObjectMapper decoratedMapper;
+
+  @Setup(Level.Trial)
+  public void setup() throws JsonProcessingException
+  {
+    final ObjectMapper undecoratedMapper = TestHelper.makeJsonMapper();
+    undecoratedMapper.registerModules(NestedDataModule.getJacksonModulesList());
+    undecoratedMapper.registerModule(new AggregatorsModule());
+    final Pair<GroupByQuery, String> sqlQueryAndResultRow = sqlQueryAndResultRow(
+        numDimensions,
+        primitiveToComplexDimensionRatio,
+        complexDimensionType,
+        undecoratedMapper
+    );
+    sqlQuery = sqlQueryAndResultRow.lhs;
+    serializedRow = sqlQueryAndResultRow.rhs;
+
+    groupByQueryQueryToolChest = new GroupByQueryQueryToolChest(
+        null,
+        () -> new GroupByQueryConfig()
+        {
+          @Override
+          public boolean isIntermediateResultAsMapCompat()
+          {
+            return backwardCompatibility;
+          }
+        },
+        null,
+        null
+    );
+
+    decoratedMapper = groupByQueryQueryToolChest.decorateObjectMapper(undecoratedMapper, sqlQuery);
+  }
+
+  @Benchmark
+  @BenchmarkMode(Mode.AverageTime)
+  @OutputTimeUnit(TimeUnit.MICROSECONDS)
+  public void deserializeResultRows(Blackhole blackhole) throws JsonProcessingException
+  {
+    blackhole.consume(decoratedMapper.readValue(serializedRow, ResultRow.class));
+  }
+
+  private static Pair<GroupByQuery, String> sqlQueryAndResultRow(
+      final int numDimensions,
+      final double primitiveToComplexDimensionRatio,
+      final String complexDimensionType,
+      final ObjectMapper mapper
+  ) throws JsonProcessingException
+  {
+    final int numPrimitiveDimensions = (int) Math.floor(primitiveToComplexDimensionRatio * numDimensions);
+    final int numComplexDimensions = numDimensions - numPrimitiveDimensions;
+
+    final List<DimensionSpec> dimensions = new ArrayList<>();
+    final List<Object> rowList = new ArrayList<>();
+
+    // Add timestamp
+    rowList.add(DateTimes.of("2000").getMillis());
+
+    for (int i = 0; i < numPrimitiveDimensions; ++i) {
+      dimensions.add(
+          new DefaultDimensionSpec(
+              StringUtils.format("primitive%d", i),
+              StringUtils.format("primitive%d", i),
+              ColumnType.STRING
+          )
+      );
+      rowList.add("foo");
+    }
+
+    for (int i = 0; i < numComplexDimensions; ++i) {
+      dimensions.add(
+          new DefaultDimensionSpec(
+              StringUtils.format("complex%d", i),
+              StringUtils.format("complex%d", i),
+              ColumnType.ofComplex(complexDimensionType)
+          )
+      );
+
+      // Serialized version of this object is a valid value for both json and long-string pair dimensions
+      rowList.add(new SerializablePairLongString(1L, "test"));
+    }
+
+    // Add aggregator
+    rowList.add(100);
+
+    // Add post aggregator
+    rowList.add(10.0);
+
+    GroupByQuery query = GroupByQuery.builder()
+                                     .setDataSource("foo")
+                                     .setQuerySegmentSpec(QueryRunnerTestHelper.FULL_ON_INTERVAL_SPEC)
+                                     .setDimensions(dimensions)
+                                     .setAggregatorSpecs(QueryRunnerTestHelper.ROWS_COUNT)
+                                     .setPostAggregatorSpecs(Collections.singletonList(new ConstantPostAggregator(
+                                         "post",
+                                         10
+                                     )))
+                                     .setContext(ImmutableMap.of(GroupByQueryConfig.CTX_KEY_ARRAY_RESULT_ROWS, true))
+                                     .setGranularity(Granularities.DAY)
+                                     .build();
+
+    return Pair.of(query, mapper.writeValueAsString(rowList));
+  }
+}

processing/src/main/java/org/apache/druid/java/util/common/jackson/JacksonUtils.java

@@ -20,8 +20,11 @@
 package org.apache.druid.java.util.common.jackson;
 
 import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.JsonToken;
 import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.DeserializationContext;
 import com.fasterxml.jackson.databind.JavaType;
 import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.JsonSerializer;
@@ -122,6 +125,40 @@ public static void writeObjectUsingSerializerProvider(
     }
   }
 
+  /**
+   * Reads an object using the {@link JsonParser}. It reuses the provided {@link DeserializationContext} which offers
+   * better performance that calling {@link JsonParser#readValueAs(Class)} because it avoids re-creating the {@link DeserializationContext}
+   * for each readValue call
+   */
+  @Nullable
+  public static <T> T readObjectUsingDeserializationContext(
+      final JsonParser jp,
+      final DeserializationContext deserializationContext,
+      final Class<T> clazz
+  ) throws IOException
+  {
+    if (jp.currentToken() == JsonToken.VALUE_NULL) {
+      return null;
+    }
+    return deserializationContext.readValue(jp, clazz);
+  }
+
+  /**
+   * @see #readObjectUsingDeserializationContext(JsonParser, DeserializationContext, Class)
+   */
+  @Nullable
+  public static Object readObjectUsingDeserializationContext(
+      final JsonParser jp,
+      final DeserializationContext deserializationContext,
+      final JavaType javaType
+  ) throws IOException
+  {
+    if (jp.currentToken() == JsonToken.VALUE_NULL) {
+      return null;
+    }
+    return deserializationContext.readValue(jp, javaType);
+  }
+
   /**
    * Convert the given object to an array of bytes. Use when the object is
    * known serializable so that the Jackson exception can be suppressed.

processing/src/main/java/org/apache/druid/query/QueryToolChest.java

@@ -88,6 +88,11 @@ public final JavaType getBySegmentResultType()
    * For most queries, this is a no-op, but it can be useful for query types that support more than one result
    * serialization format. Queries that implement this method must not modify the provided ObjectMapper, but instead
    * must return a copy.
+   * <p>
+   * Jackson's default implementation of deserialization is usually optimised and this method should be overriden
+   * only if there is a functional requirement of so. The method must be benchmarked in isolation, without other portions
+   * of the query engine executing as modifying this method can alter the performance of queries where deserializing is
+   * a major portion of the execution.
    */
   public ObjectMapper decorateObjectMapper(final ObjectMapper objectMapper, final QueryType query)
   {

processing/src/main/java/org/apache/druid/query/groupby/GroupByQueryConfig.java

@@ -293,7 +293,6 @@ public boolean isVectorize()
     return vectorize;
   }
 
-  @SuppressWarnings("unused")
   public boolean isIntermediateResultAsMapCompat()
   {
     return intermediateResultAsMapCompat;