我正在尝试使用亚马逊的EMR服务在现场实例上运行MapReduce作业。目的是从S3读取文件，在MR作业中处理它们，并将行发送到reducer中的Cassandra DB。
我的自定义jar在我的计算机上托管的单节点Hadoop集群上正常运行，从S3读取文件并将行发送到云托管的Cassandra集群。
在EMR现场实例上运行，我的作业完成其地图阶段没有问题，然后在缩减阶段抛出以下错误：
2013-07-09 17:23:46,598 FATAL org.apache.hadoop.mapred.Child (main): Error running child : java.lang.NoSuchMethodError: org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder.<init>(IIIIIZ)V
at org.apache.cassandra.transport.Frame$Decoder.<init>(Frame.java:147)
at com.datastax.driver.core.Connection$PipelineFactory.getPipeline(Connection.java:616)
at org.jboss.netty.bootstrap.ClientBootstrap.connect(ClientBootstrap.java:212)
at org.jboss.netty.bootstrap.ClientBootstrap.connect(ClientBootstrap.java:188)
at com.datastax.driver.core.Connection.<init>(Connection.java:111)
at com.datastax.driver.core.Connection.<init>(Connection.java:56)
at com.datastax.driver.core.Connection$Factory.open(Connection.java:387)
at com.datastax.driver.core.ControlConnection.tryConnect(ControlConnection.java:211)
at com.datastax.driver.core.ControlConnection.reconnectInternal(ControlConnection.java:174)
at com.datastax.driver.core.ControlConnection.connect(ControlConnection.java:87)
at com.datastax.driver.core.Cluster$Manager.init(Cluster.java:609)
at com.datastax.driver.core.Cluster$Manager.access$100(Cluster.java:553)
at com.datastax.driver.core.Cluster.<init>(Cluster.java:67)
at com.datastax.driver.core.Cluster.buildFrom(Cluster.java:94)
at com.datastax.driver.core.Cluster$Builder.build(Cluster.java:534)
at com.fullcontact.photo_deduplication.metadata.MetaToCassandraReducer.setup(MetaToCassandraReducer.java:32)
at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:174)
at org.apache.hadoop.mapred.ReduceTask.runNewReducer(ReduceTask.java:663)
at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:426)
at org.apache.hadoop.mapred.Child$4.run(Child.java:255)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1132)
at org.apache.hadoop.mapred.Child.main(Child.java:249)
Gradle报告我唯一的netty依赖项是版本3.6.3，它有一个版本的ctor。
我的机器和EMR之间可能会有什么不同会导致此错误？或者它可能完全是另一回事？