java - hadoop NoClassDefFoundError 尽管 DistributedCache 设置

Question

我试图摆脱一些NoClassDefFoundError由于一些 jars运行时找不到。所以我输入了我的hdfs系统一些库，我打电话，我把这个

String lib = "/path/to/lib";
Path hdfsJar = new Path(lib);
DistributedCache.addFileToClassPath(hdfsJar, conf); 

现在，我仍然收到错误消息。但是，如果我设置 jars在 $HADOOP_CLASSPATH .我对 DistributedCache 做错了吗？称呼 ？

编辑 :

java.lang.RuntimeException: java.lang.NoClassDefFoundError: gov/nih/nlm/nls/metamap/MetaMapApi
    at org.apache.hadoop.mapreduce.lib.chain.Chain.joinAllThreads(Chain.java:526)
    at org.apache.hadoop.mapreduce.lib.chain.ChainMapper.run(ChainMapper.java:169)
    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:784)
    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
    at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:415)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)
    at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)
Caused by: java.lang.NoClassDefFoundError: gov/nih/nlm/nls/metamap/MetaMapApi
    at org.avrosation.metamap.ChainMetaProcess$TokenizerMapper.map(ChainMetaProcess.java:25)
    at org.avrosation.metamap.ChainMetaProcess$TokenizerMapper.map(ChainMetaProcess.java:16)
    at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:145)
    at org.apache.hadoop.mapreduce.lib.chain.Chain$MapRunner.run(Chain.java:321)
Caused by: java.lang.ClassNotFoundException: gov.nih.nlm.nls.metamap.MetaMapApi
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358) 

Answer 1

尝试提供完全合格的 HDFS 路径。试试下面的代码:

确保将 jar 上传到 HDFS(hdfs 上的任何位置，我假设/tmp)。

hadoop fs -copyFromLocal my.jar /tmp

然后编辑您的java代码，如:

String lib = "hdfs://localhost:9000/tmp/my.jar";
Path hdfsJar = new Path(lib);
DistributedCache.addFileToClassPath(hdfsJar, conf); 

这篇关于分布式缓存的文档详细信息: https://hadoop.apache.org/docs/stable/api/org/apache/hadoop/filecache/DistributedCache.html