hadoop -libjars和ClassNotFoundException

本文介绍了hadoop -libjars和ClassNotFoundException的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 请帮助，我卡住了。 这里是我的代码来运行作业。 hadoop jar mrjob.jar ru.package.Main -files hdfs： //0.0.0.0:8020/MyCatalog/jars/metadata.csv -libjars hdfs：//0.0.0.0:8020/ MyCatalog / jars / opencsv.jar，hdfs：//0.0.0.0:8020/ MyCatalog / jars / gson .jar，hdfs：//0.0.0.0:8020/ MyCatalog / jars / my-utils.jar /MyCatalog/http_requests.seq-r-00000/ MyCatalog / output / result_file 我得到这些警告： 12/10 / 26 18:35:50 WARN util.GenericOptionsParser：libjars文件hdfs：//0.0.0.0:8020/MyCatalog/jars/opencsv.jar不在本地文件系统中。忽略。 12/10/26 18:35:50 WARN util.GenericOptionsParser：libjars文件hdfs：//0.0.0.0:8020/MyCatalog/jars/gson.jar不在本地文件系统中。忽略。 12/10/26 18:35:50 WARN util.GenericOptionsParser：libjars文件hdfs：//0.0.0.0:8020/ MyCatalog / jars / my-utils.jar不在本地文件系统中。忽略。 然后：线程main中的异常java.lang.NoClassDefFoundError： 在Main类中，我尝试从名为my-utils.jar的jar实例化类。 $ b $ ol 所有这些jar都在hfds（我通过文件浏览器看到它们） my-utils.jar包含的类是 NoClassDefFoundError 的原因 我做错了什么？ UPD：检查 GenericOptionsParser 的源代码： / ** *如果libjars设置为conf，解析libjars。 * @param conf * @return libjar url * @throws IOException * / public static URL [] getLibJars（Configuration conf）throws IOException { String jars = conf.get（tmpjars）; if（jars == null）{ return null; } String [] files = jars.split（，）; 列表<网址> cp = new ArrayList< URL>（）; for（String file：files）{ Path tmp = new Path（file）; if（tmp.getFileSystem（conf）.equals（FileSystem.getLocal（conf）））{ cp.add（FileSystem.getLocal（conf）.pathToFile（tmp）.toURI（）。toURL ））; } else { LOG.warn（libjars文件+ tmp +不在本地的+ 文件系统中，忽略。）; } } 返回cp.toArray（新URL [0]）; $ / code> 所以： 1.逗号之间不能有空格 2.仍然不明白...我试过指向：本地文件系统，hdfs文件系统，结果是一样的。似乎没有添加类... 解决方案问题解决了。正确的调用是： hadoop jar my-job.jar ru.package.Main -files / home / cloudera / uploaded_jars / metadata .csv -libjars /home/cloudera/uploaded_jars/opencsv.jar,/home/cloudera/uploaded_jars/gson.jar,/home/cloudera/uploaded_jars/url-raiting-utils.jar /MyCatalog/http_requests.seq-r-00000 / MyCatalog / output / scoring_result 其中 是hdfs路径， / home / cloudera / uploaded_jars / 是本地fs路径 问题出现在job jar中。 之前，我曾尝试使用简单的jar 运行作业，只有三个类：Mapper，Reducer，Main class 。 现在我确实提供了另一个由maven生成的（它生成其中两个） 第二个作业jar包含所有依赖库。在里面。结构如下所示： my-job.jar - lib - aopalliance-1.0.jar asm-3.2.jar avro-1.5.4.jar ... commons-beanutils-1.7.0.jar commons-beanutils-core-1.8 .0.jar ... zookeeper-3.4.3-cdh4.0.0.jar lib文件夹中有76个jar。 它可以工作，但我不明白为什么。 please help, I'm stuck.Here is my code to run job.hadoop jar mrjob.jar ru.package.Main -files hdfs://0.0.0.0:8020/MyCatalog/jars/metadata.csv -libjars hdfs://0.0.0.0:8020/MyCatalog/jars/opencsv.jar,hdfs://0.0.0.0:8020/MyCatalog/jars/gson.jar,hdfs://0.0.0.0:8020/MyCatalog/jars/my-utils.jar /MyCatalog/http_requests.seq-r-00000 /MyCatalog/output/result_fileI do get these WARNs:12/10/26 18:35:50 WARN util.GenericOptionsParser: The libjars file hdfs://0.0.0.0:8020/MyCatalog/jars/opencsv.jar is not on the local filesystem. Ignoring.12/10/26 18:35:50 WARN util.GenericOptionsParser: The libjars file hdfs://0.0.0.0:8020/MyCatalog/jars/gson.jar is not on the local filesystem. Ignoring.12/10/26 18:35:50 WARN util.GenericOptionsParser: The libjars file hdfs://0.0.0.0:8020/MyCatalog/jars/my-utils.jar is not on the local filesystem. Ignoring.Then: Exception in thread "main" java.lang.NoClassDefFoundError:on line in Main class where I try to instantiate class from jar named my-utils.jarAll these jars are in hfds (I see them through file browser)my-utils.jar does contain class which is a reason for NoClassDefFoundErrorWhat do I do wrong?UPD:I'm inspecting sourcecode of GenericOptionsParser:/** * If libjars are set in the conf, parse the libjars. * @param conf * @return libjar urls * @throws IOException */ public static URL[] getLibJars(Configuration conf) throws IOException { String jars = conf.get("tmpjars"); if(jars==null) { return null; } String[] files = jars.split(","); List<URL> cp = new ArrayList<URL>(); for (String file : files) { Path tmp = new Path(file); if (tmp.getFileSystem(conf).equals(FileSystem.getLocal(conf))) { cp.add(FileSystem.getLocal(conf).pathToFile(tmp).toURI().toURL()); } else { LOG.warn("The libjars file " + tmp + " is not on the local " + "filesystem. Ignoring."); } } return cp.toArray(new URL[0]); }So:1. no spaces between comma2. still don't get it... I've tried to point to: local file system, hdfs file system, result is the same. Seems like class is not added... 解决方案 Problem is solved. correct invocation is:hadoop jar my-job.jar ru.package.Main -files /home/cloudera/uploaded_jars/metadata.csv -libjars /home/cloudera/uploaded_jars/opencsv.jar,/home/cloudera/uploaded_jars/gson.jar,/home/cloudera/uploaded_jars/url-raiting-utils.jar /MyCatalog/http_requests.seq-r-00000 /MyCatalog/output/scoring_resultwhere is hdfs path, is local fs pathThe problem was in job jar.Previously I did try to run job using simple jar with only three classes: Mapper, Reducer, Main class.Now I did provide other one generated by maven (it generates two of them)The second job jar contains all dependency libs. in side it. Structure looks like:my-job.jar-lib--aopalliance-1.0.jar asm-3.2.jar avro-1.5.4.jar ... commons-beanutils-1.7.0.jar commons-beanutils-core-1.8.0.jar ... zookeeper-3.4.3-cdh4.0.0.jar There are 76 jars inside lib folder.It works but I don't understand why. 这篇关于hadoop -libjars和ClassNotFoundException的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！