Question

最近几天我一直在试验Hadoop。我在Ubuntu 12.10上以伪分布式模式运行Hadoop并成功执行了一些标准的MapReduce作业。

接下来我想开始尝试HBase。我已经安装了HBase，在shell中玩了一下。这一切都很顺利所以我想通过一个简单的Java程序来试验HBase。我想导入之前MapReduce作业之一的输出并将其加载到HBase表中。我写了一个Mapper，它应该生成HFileOutputFormat个文件，这些文件应该很容易读入HBase表。

现在，每当我运行程序时（使用：hadoop jar [编译jar]），我得到一个ClassNotFoundException。该程序似乎无法解决com.google.commons.primitives.Long。当然，我认为这只是一个依赖缺失，但JAR（Google的Guava）就在那里。

我尝试了很多不同的东西，但似乎无法找到解决方案。

我附加了发生的异常和最重要的类。如果有人可以帮助我或者给我一些关于在哪里看的建议，我将非常感激。

亲切的问候， Pieterjan

错误

12/12/13 09:02:54 WARN snappy.LoadSnappy: Snappy native library not loaded
12/12/13 09:03:00 INFO mapred.JobClient: Running job: job_201212130304_0020
12/12/13 09:03:01 INFO mapred.JobClient:  map 0% reduce 0%
12/12/13 09:04:07 INFO mapred.JobClient:  map 100% reduce 0%
12/12/13 09:04:51 INFO mapred.JobClient: Task Id : attempt_201212130304_0020_r_000000_0,Status : FAILED
Error: java.lang.ClassNotFoundException: com.google.common.primitives.Longs
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
    at org.apache.hadoop.hbase.KeyValue$KVComparator.compare(KeyValue.java:1554)
    at org.apache.hadoop.hbase.KeyValue$KVComparator.compare(KeyValue.java:1536)
    at java.util.TreeMap.compare(TreeMap.java:1188)
    at java.util.TreeMap.put(TreeMap.java:531)
    at java.util.TreeSet.add(TreeSet.java:255)
    at org.apache.hadoop.hbase.mapreduce.PutSortReducer.reduce(PutSortReducer.java:63)
    at org.apache.hadoop.hbase.mapreduce.PutSortReducer.reduce(PutSortReducer.java:40)
    at org.apache.hadoop.mapreduce.Reducer.run(Reducer.java:176)
    at org.apache.hadoop.mapred.ReduceTask.runNewReducer(ReduceTask.java:650)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:418)
    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:415)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1136)
    at org.apache.hadoop.mapred.Child.main(Child.java:249)

JAVA
的映射器：

public class TestHBaseMapper extends Mapper<LongWritable, Text, ImmutableBytesWritable, Put> {

@Override
public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
    //Tab delimiter \t, white space delimiter: \\s+
    String[] s = value.toString().split("\t"); 
    Put put = new Put(s[0].getBytes());
    put.add("amount".getBytes(), "value".getBytes(), value.getBytes());      
    context.write(new ImmutableBytesWritable(Bytes.toBytes(s[0])), put);
}

作业：

public class TestHBaseRun extends Configured implements Tool {

@Override
public int run(String[] args) throws Exception {
    try {
        Configuration configuration = getConf();

        Job hbasejob = new Job(configuration);
        hbasejob.setJobName("TestHBaseJob");
        hbasejob.setJarByClass(TestHBaseRun.class);

        //Specifies the InputFormat and the path.
        hbasejob.setInputFormatClass(TextInputFormat.class);
        TextInputFormat.setInputPaths(hbasejob, new Path("/hadoopdir/user/data/output/test/"));

        //Set Mapper, MapperOutputKey and MapperOutputValue classes.
        hbasejob.setMapperClass(TestHBaseMapper.class);
        hbasejob.setMapOutputKeyClass(ImmutableBytesWritable.class);
        hbasejob.setMapOutputValueClass(Put.class);

        //Specifies the OutputFormat and the path. If The path exists it's reinitialized.
        //In this case HFiles, that can be imported into HBase, are produced.
        hbasejob.setOutputFormatClass(HFileOutputFormat.class);
        FileSystem fs = FileSystem.get(configuration);
        Path outputpath = new Path("/hadoopdir/user/data/hbase/table/");
        fs.delete(outputpath, true);
        HFileOutputFormat.setOutputPath(hbasejob, outputpath);

        //Check if table exists in HBase and creates it if necessary.
        HBaseUtil util = new HBaseUtil(configuration);
        if (!util.exists("test")) {
            util.createTable("test", new String[]{"amount"});
        }

        //Reads the existing (or thus newly created) table.
        Configuration hbaseconfiguration = HBaseConfiguration.create(configuration);
        HTable table = new HTable(hbaseconfiguration, "test");

        //Write HFiles to disk. Autoconfigures partitioner and reducer.
        HFileOutputFormat.configureIncrementalLoad(hbasejob, table);

        boolean success = hbasejob.waitForCompletion(true);

        //Load generated files into table.
        LoadIncrementalHFiles loader;
        loader = new LoadIncrementalHFiles(hbaseconfiguration);
        loader.doBulkLoad(outputpath, table);

        return success ? 0 : 1;
    } catch (Exception ex) {
        System.out.println("Error: " + ex.getMessage());
    }
    return 1;
}

Answer 1

ClassNotFoundException ，表示无法找到包含com.google.common.primitives.Longs所需的.jar。

有几种方法可以解决这个问题：

如果您只是在玩Hadoop，解决此问题的最简单方法是将所需的.jar复制到 / usr / share / hadoop / lib 中。
将所需.jar的路径添加到HADOOP_CLASSPATH。为此，请打开 /etc/hbase/hbase-env.sh 并添加：

export HADOOP_CLASSPATH =“＆lt; jar_files＆gt;：$ HADOOP_CLASSPATH”
在根项目文件夹中创建文件夹 / lib 。将.jar复制到该文件夹中。为您的项目创建一个包（.jar）。结果将是一个包含 / lib 中包含的所有jar的胖罐。

将MapReduce输出数据加载到HBase中

1 个答案: