[SAMZA-933] SamzaObjectMapper used in JsonSerde has disabled the auto_detect_getters

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.10.0
• Fix Version/s: 0.10.1
• Component/s: container
• Assignee: Yuanchi Ning
• Reporter: Yuanchi Ning
• Created: 07/Apr/16 18:52
• Updated: 14/Apr/16 21:13
• Resolved: 14/Apr/16 21:13

Description

Find there is a bug in the new version JsonSerde file in Samza 0.10.0, it replaced the codehaus ObjectMapper with SamzaObjectMapper and in the SamzaObjectMapper there is one line:

mapper.configure(SerializationConfig.Feature.AUTO_DETECT_GETTERS, false);

In the code comment we can see:

/**

• Feature that determines whether regualr "getter" methods are
• automatically detected based on standard Bean naming convention
• or not. If yes, then all public zero-argument methods that
• start with prefix "get"
• are considered as getters.
• If disabled, only methods explicitly annotated are considered getters.
  *<p>
• Note that since version 1.3, this does <b>NOT</b> include
• "is getters" (see
  Unknown macro: {@link #AUTO_DETECT_IS_GETTERS}

  for details)
  *<p>

• Note that this feature has lower precedence than per-class
• annotations, and is only used if there isn't more granular
• configuration available.
  *<P>
• Feature is enabled by default.
  */
  AUTO_DETECT_GETTERS(true),

Which causes the Serde fail to serialize the HashMap entry object in hello-athena example.
To verify that, I wrote a simple code to test it out:

package com.uber.athena;

import java.util.HashMap;
import java.util.Map;

import org.apache.samza.serializers.JsonSerde;

public class SerializationHMEntry {
public static void main(String[] args) {
JsonSerde jsonSerde = new JsonSerde();
Map<String, Long> dummyHashMap = new HashMap<>();
dummyHashMap.put("key1", 1L);
for (Map.Entry<String, Long> entry : dummyHashMap.entrySet())

Unknown macro: { byte[] bytes = jsonSerde.toBytes(entry); System.out.println(bytes.toString()); }

}
}

The output exception is as below:

Exception in thread "main" org.apache.samza.SamzaException: org.codehaus.jackson.map.JsonMappingException: No serializer found for class java.util.HashMap$Node and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS) )
at org.apache.samza.serializers.JsonSerde.toBytes(JsonSerde.scala:36)
at com.uber.athena.SerializationHMEntry.main(SerializationHMEntry.java:16)
Caused by: org.codehaus.jackson.map.JsonMappingException: No serializer found for class java.util.HashMap$Node and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS) )
at org.codehaus.jackson.map.ser.StdSerializerProvider$1.failForEmpty(StdSerializerProvider.java:89)
at org.codehaus.jackson.map.ser.StdSerializerProvider$1.serialize(StdSerializerProvider.java:62)
at org.codehaus.jackson.map.ser.StdSerializerProvider._serializeValue(StdSerializerProvider.java:600)
at org.codehaus.jackson.map.ser.StdSerializerProvider.serializeValue(StdSerializerProvider.java:280)
at org.codehaus.jackson.map.ObjectMapper._configAndWriteValue(ObjectMapper.java:2260)
at org.codehaus.jackson.map.ObjectMapper.writeValueAsString(ObjectMapper.java:1829)
at org.apache.samza.serializers.JsonSerde.toBytes(JsonSerde.scala:33)
... 1 more

And if commented out that line in the Samza 0.10.0 SamzaObjectMapper file and rebuild Samza as the dependency, the sample code works fine.