我在eclipse中使用run as hadoop执行程序时遇到Mapper类错误，但是当我通过创建jar执行它正常工作时
我检查了classpath中的所有类。 我需要将这个MapReduce程序从eclipse连接到后端进程..
public class DBDriver extends Configured implements Tool {
public int run(String[] args) throws Exception {
// TODO Auto-generated method stub
//Configuration conf = new Configuration();
String dbName = "bigdata";
String tableName = "cpr_transaction";
Job job = Job.getInstance(getConf());
HCatInputFormat.setInput(job, dbName, tableName);
job.setJarByClass(DBDriver.class);
//job.setJar("/home/murali/workspace/hadoop/DBReader/target/DBReader-0.0.1-SNAPSHOT.jar");
job.setMapperClass(DBMapper.class);
job.setReducerClass(DBReducer.class);
job.setInputFormatClass(HCatInputFormat.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(Text.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(DoubleWritable.class);
FileOutputFormat.setOutputPath(job, new Path("/user/murali/output/HiveIO"));
return(job.waitForCompletion(true)? 0:1);
}
public static void main(String[] args) throws Exception {
int exitStatus = ToolRunner.run(new DBDriver(), args);
System.exit(exitStatus);
}
public static class DBMapper extends Mapper<Writable, HCatRecord, Text, Text> {
String amount;
String outlet;
public void map(Writable key, HCatRecord value, Mapper<Writable, HCatRecord, Text, Text>.Context context) throws IOException, InterruptedException {
amount = (String) value.get(8);
outlet = (String) value.get(3);
context.write(new Text(outlet), new Text(amount));
}
}
public class DBReducer extends Reducer<Text, Text, Text, DoubleWritable> {
public void reduce(Text key, Iterable<Text> values, Reducer<Text, Text, Text, DoubleWritable>.Context context) throws IOException, InterruptedException {
double totalAmount = 0.0;
for (Text text : values) {
String textStr = text.toString();
textStr = textStr.replaceAll(",", "");
if (!(textStr.equalsIgnoreCase(null))) {
totalAmount += Double.parseDouble(textStr.toString());
}
}
context.write(key, new DoubleWritable(totalAmount));
}
}
}
我得到的错误是
14/12/11 14:57:04 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
14/12/11 14:57:04 INFO hive.metastore: Trying to connect to metastore with URI thrift://192.168.0.65:9083
14/12/11 14:57:04 INFO hive.metastore: Connected to metastore.
14/12/11 14:57:05 INFO client.RMProxy: Connecting to ResourceManager at hdm/192.168.0.93:8032
14/12/11 14:57:06 WARN mapreduce.JobSubmitter: No job jar file set. User classes may not be found. See Job or Job#setJar(String).
14/12/11 14:57:06 INFO Configuration.deprecation: mapred.input.dir is deprecated. Instead, use mapreduce.input.fileinputformat.inputdir
14/12/11 14:57:06 INFO mapred.FileInputFormat: Total input paths to process : 1
14/12/11 14:57:06 INFO mapreduce.JobSubmitter: number of splits:1
14/12/11 14:57:06 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1418017495640_0166
14/12/11 14:57:06 INFO mapred.YARNRunner: Job jar is not present. Not adding any jar to the list of resources.
14/12/11 14:57:06 INFO impl.YarnClientImpl: Submitted application application_1418017495640_0166
14/12/11 14:57:06 INFO mapreduce.Job: The url to track the job: http://hdm:8088/proxy/application_1418017495640_0166/
14/12/11 14:57:06 INFO mapreduce.Job: Running job: job_1418017495640_0166
14/12/11 14:57:11 INFO mapreduce.Job: Job job_1418017495640_0166 running in uber mode : false
14/12/11 14:57:11 INFO mapreduce.Job: map 0% reduce 0%
14/12/11 14:57:14 INFO mapreduce.Job: Task Id : attempt_1418017495640_0166_m_000000_0, Status : FAILED
Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class com.cosn.DBReader.DBDriver$DBMapper not found
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1905)
at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:722)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
Caused by: java.lang.ClassNotFoundException: Class com.cosn.DBReader.DBDriver$DBMapper not found
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:1811)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1903)
... 8 more
14/12/11 14:57:18 INFO mapreduce.Job: Task Id : attempt_1418017495640_0166_m_000000_1, Status : FAILED
Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class com.cosn.DBReader.DBDriver$DBMapper not found
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1905)
at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:722)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
Caused by: java.lang.ClassNotFoundException: Class com.cosn.DBReader.DBDriver$DBMapper not found
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:1811)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1903)
... 8 more
14/12/11 14:57:22 INFO mapreduce.Job: Task Id : attempt_1418017495640_0166_m_000000_2, Status : FAILED
Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class com.cosn.DBReader.DBDriver$DBMapper not found
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1905)
at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:722)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:340)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:168)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:163)
Caused by: java.lang.ClassNotFoundException: Class com.cosn.DBReader.DBDriver$DBMapper not found
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:1811)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:1903)
... 8 more
14/12/11 14:57:27 INFO mapreduce.Job: map 100% reduce 100%
14/12/11 14:57:27 INFO mapreduce.Job: Job job_1418017495640_0166 failed with state FAILED due to: Task failed task_1418017495640_0166_m_000000
Job failed as tasks failed. failedMaps:1 failedReduces:0
14/12/11 14:57:27 INFO mapreduce.Job: Counters: 9
Job Counters
Failed map tasks=4
Launched map tasks=4
Other local map tasks=3
Data-local map tasks=1
Total time spent by all maps in occupied slots (ms)=8314
Total time spent by all reduces in occupied slots (ms)=0
Total time spent by all map tasks (ms)=8314
Total vcore-seconds taken by all map tasks=8314
Total megabyte-seconds taken by all map tasks=8513536
答案 0 :(得分：0)
尝试在reducer中包含“ static ”以及
public static class DBReducer extends Reducer<Text, Text, Text, DoubleWritable> {
public void reduce(Text key, Iterable<Text> values, Reducer<Text, Text, Text, DoubleWritable>.Context context) throws IOException, InterruptedException {