我想序列化一个Java类,其对象将在Java Spark RDD中收集。 POJO包含一些数据结构,如HashMap
和ArrayList
。HashMap的火花序列化问题
当我试图迭代我的驱动程序中的RDD
对象并尝试获取hashmap
元素时,它抛出了Serialization exception
。
产生java.io.IOException:com.esotericsoftware.kryo.KryoException:显示java.lang.NullPointerException
示例程序:
驱动程序类:
主要Implementaion:
public class MyMainTest {
public static ArrayList<MyInterface> call() throws Exception{
ArrayList<MyInterface> li = new ArrayList<MyInterface>();
for(int i=0;i<3;i++){
MyRecord myrec = new MyRecord();
li.add(myrec.addToTagMap());
}
return li;
}
}
Main Implementation:
public class MyMainTest {
public static ArrayList<MyInterface> call() throws Exception{
ArrayList<MyInterface> li = new ArrayList<MyInterface>();
for(int i=0;i<3;i++){
MyRecord myrec = new MyRecord();
li.add(myrec.addToTagMap());
}
return li;
}
}
My Pojo Class:
public class MyRecord implements MyInterface,Serializable{
protected HashMap<String, Object> allTagNameValueMap_
= new HashMap<String, Object>(){
{
put("key1", "T1");
put("key2", "Val2");
put("key3", 3);
}};
protected MyRecord addToTagMap() throws Exception {
MyRecord myRec = new MyRecord();
myRec.allTagNameValueMap_.put("key1", "New Value");
myRec.allTagNameValueMap_.put("key2", "New Value2");
myRec.allTagNameValueMap_.put("key4", 22);
return myRec;
}
@Override
public Object getKey1() {
// TODO Auto-generated method stub
return allTagNameValueMap_.get("key1");
}
@Override
public Object getKey2() {
// TODO Auto-generated method stub
return allTagNameValueMap_.get("key2");
}
@Override
public Object getKey3() {
// TODO Auto-generated method stub
return allTagNameValueMap_.get("key3");
}
}
My Interface:
public interface MyInterface extends Serializable{
public Object getKey1();
public Object getKey2();
public Object getKey3();
}
序列化轨迹:
allTagNam eValueMap_(com.org.util.ex.ExRecord)
at org.apache.spark.util.Utils$.tryOrIOException(Utils.scala:1140)
at org.apache.spark.rdd.ParallelCollectionPartition.readObject(ParallelCollectionRDD.scala:70)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1893)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1990)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1915)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370)
at org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:68)
at org.apache.spark.serializer.JavaSerializerInstance.deserialize(JavaSerializer.scala:94)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:185)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
引起:com.esotericsoftware.kryo.KryoException:显示java.lang.NullPointerException 序列化迹:
allTagNameValueMap_(com.org.util .ex.ExRecord)
at com.esotericsoftware.kryo.serializers.FieldSerializer$ObjectField.read(FieldSerializer.java:626)
at com.esotericsoftware.kryo.serializers.FieldSerializer.read(FieldSerializer.java:221)
at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:729)
at com.esotericsoftware.kryo.serializers.DefaultArraySerializers$ObjectArraySerializer.read(DefaultArraySerializers.java:338)
at com.esotericsoftware.kryo.serializers.DefaultArraySerializers$ObjectArraySerializer.read(DefaultArraySerializers.java:293)
at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:729)
at com.twitter.chill.WrappedArraySerializer.read(WrappedArraySerializer.scala:36)
at com.twitter.chill.WrappedArraySerializer.read(WrappedArraySerializer.scala:23)
at com.esotericsoftware.kryo.Kryo.readClassAndObject(Kryo.java:729)
at org.apache.spark.serializer.KryoDeserializationStream.readObject(KryoSerializer.scala:138)
at org.apache.spark.rdd.ParallelCollectionPartition$$anonfun$readObject$1$$anonfun$apply$mcV$sp$2.apply(ParallelCollectionRDD.scala:80)
at org.apache.spark.rdd.ParallelCollectionPartition$$anonfun$readObject$1$$anonfun$apply$mcV$sp$2.apply(ParallelCollectionRDD.scala:80)
at org.apache.spark.util.Utils$.deserializeViaNestedStream(Utils.scala:130)
at org.apache.spark.rdd.ParallelCollectionPartition$$anonfun$readObject$1.apply$mcV$sp(ParallelCollectionRDD.scala:80)
at org.apache.spark.util.Utils$.tryOrIOException(Utils.scala:1137)
... 20 more
产生的原因:在java.util.HashMap.put(HashMap.java:493显示java.lang.NullPointerException ) 在com.esotericsoftware.kryo.serializers.MapSerializer.read( MapSerializer.java:135 ) at com.esotericsoftware.kryo.serializers.MapSerializer.read(MapSerializer.java:17) at com.esotericsoftware.kryo.Kryo.readObject(Kryo.java:648) at com.esotericsoftware.kryo.serializers.FieldSerializer $ ObjectField.read(FieldSerializer.java:605)
在序列化HashMap
在Spark
中有什么特别的地方需要注意吗?
请问您可以编辑日志使其更容易阅读 –
欢迎来到SO Hari。您可以提供[MCVE](http://stackoverflow.com/help/mcve)吗?这对帮助你更容易,对更多的读者更有用。在此期间检查[this](http://stackoverflow.com/a/33042316/1560062)。 – zero323
谢谢。 zero323 我应该对MyKryoRegistrator一个电话从我的驱动程序的,然后设置sparkConf序列化作为KryoSerializable – Harisyam