如何修复java.lang.ClassCastException:无法将scala.collection.immutable.List的实例分配给字段类型scala.collection.Seq?
2022-09-03 12:41:50
此错误是最难追踪的。我不确定发生了什么。我正在位置计算机上运行 Spark 群集。所以整个火花集群都在一个主机下,我在独立模式下运行。127.0.0.1
JavaPairRDD<byte[], Iterable<CassandraRow>> cassandraRowsRDD= javaFunctions(sc).cassandraTable("test", "hello" )
.select("rowkey", "col1", "col2", "col3", )
.spanBy(new Function<CassandraRow, byte[]>() {
@Override
public byte[] call(CassandraRow v1) {
return v1.getBytes("rowkey").array();
}
}, byte[].class);
Iterable<Tuple2<byte[], Iterable<CassandraRow>>> listOftuples = cassandraRowsRDD.collect(); //ERROR HAPPENS HERE
Tuple2<byte[], Iterable<CassandraRow>> tuple = listOftuples.iterator().next();
byte[] partitionKey = tuple._1();
for(CassandraRow cassandraRow: tuple._2()) {
System.out.println("************START************");
System.out.println(new String(partitionKey));
System.out.println("************END************");
}
此错误是最难追踪的。它显然发生在我不知道为什么?cassandraRowsRDD.collect()
16/10/09 23:36:21 ERROR Executor: Exception in task 2.3 in stage 0.0 (TID 21)
java.lang.ClassCastException: cannot assign instance of scala.collection.immutable.List$SerializationProxy to field org.apache.spark.rdd.RDD.org$apache$spark$rdd$RDD$$dependencies_ of type scala.collection.Seq in instance of org.apache.spark.rdd.MapPartitionsRDD
at java.io.ObjectStreamClass$FieldReflector.setObjFieldValues(ObjectStreamClass.java:2133)
at java.io.ObjectStreamClass.setObjFieldValues(ObjectStreamClass.java:1305)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2006)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1924)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:2000)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1924)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
at org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:75)
at org.apache.spark.serializer.JavaSerializerInstance.deserialize(JavaSerializer.scala:114)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
at org.apache.spark.scheduler.Task.run(Task.scala:85)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:274)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
以下是我使用的版本
Scala code runner version 2.11.8 // when I run scala -version or even ./spark-shell
compile group: 'org.apache.spark' name: 'spark-core_2.11' version: '2.0.0'
compile group: 'org.apache.spark' name: 'spark-streaming_2.11' version: '2.0.0'
compile group: 'org.apache.spark' name: 'spark-sql_2.11' version: '2.0.0'
compile group: 'com.datastax.spark' name: 'spark-cassandra-connector_2.11' version: '2.0.0-M3':
我的gradle文件在引入一个名为“提供”的东西后看起来像这样,实际上似乎并不存在,但谷歌说要创建一个,所以我的build.gradle看起来像这样
group 'com.company'
version '1.0-SNAPSHOT'
apply plugin: 'java'
apply plugin: 'idea'
repositories {
mavenCentral()
mavenLocal()
}
configurations {
provided
}
sourceSets {
main {
compileClasspath += configurations.provided
test.compileClasspath += configurations.provided
test.runtimeClasspath += configurations.provided
}
}
idea {
module {
scopes.PROVIDED.plus += [ configurations.provided ]
}
}
dependencies {
compile 'org.slf4j:slf4j-log4j12:1.7.12'
provided group: 'org.apache.spark', name: 'spark-core_2.11', version: '2.0.0'
provided group: 'org.apache.spark', name: 'spark-streaming_2.11', version: '2.0.0'
provided group: 'org.apache.spark', name: 'spark-sql_2.11', version: '2.0.0'
provided group: 'com.datastax.spark', name: 'spark-cassandra-connector_2.11', version: '2.0.0-M3'
}
jar {
from { configurations.provided.collect { it.isDirectory() ? it : zipTree(it) } }
// with jar
from sourceSets.test.output
manifest {
attributes 'Main-Class': "com.company.batchprocessing.Hello"
}
exclude 'META-INF/.RSA', 'META-INF/.SF', 'META-INF/*.DSA'
zip64 true
}