【Hadoop】Hadoop MR异常处理

1、代码示例

package com.ares.hadoop.mr.flowsort;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.NullWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.util.StringUtils;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.log4j.Logger;

import com.ares.hadoop.mr.exception.LineException;

public class FlowSort extends Configured implements Tool {
    private static final Logger LOGGER = Logger.getLogger(FlowSort.class);
    enum Counter {
        LINESKIP
    }
    
    public static class FlowSortMapper extends Mapper<LongWritable, Text, 
        FlowBean, NullWritable> {
        private String line;
        private int length;
        private final static char separator = '	';
        
        private String phoneNum;
        private long upFlow;
        private long downFlow;
        private long sumFlow;
        
        private FlowBean flowBean = new FlowBean();
        private NullWritable nullWritable = NullWritable.get();
        
        @Override
        protected void map(
                LongWritable key,
                Text value,
                Mapper<LongWritable, Text, FlowBean, NullWritable>.Context context)
                throws IOException, InterruptedException {
            // TODO Auto-generated method stub
            //super.map(key, value, context);
            String errMsg;
            try {
                line = value.toString();
                String[] fields = StringUtils.split(line, separator);
                length = fields.length;
                if (length != 4) {
                    throw new LineException(key.get() + ", " + line + " LENGTH INVALID, IGNORE...");
                }
                
                phoneNum = fields[0];
                upFlow = Long.parseLong(fields[1]);
                downFlow = Long.parseLong(fields[2]);
                sumFlow = Long.parseLong(fields[3]);
                
                flowBean.setPhoneNum(phoneNum);
                flowBean.setUpFlow(upFlow);
                flowBean.setDownFlow(downFlow);
                flowBean.setSumFlow(sumFlow);
                
                context.write(flowBean, nullWritable);
            } catch (LineException e) {
                // TODO: handle exception
                LOGGER.error(e);
                System.out.println(e);
                context.getCounter(Counter.LINESKIP).increment(1);
                return;
            } catch (NumberFormatException e) {
                // TODO: handle exception
                errMsg = key.get() + ", " + line + " FLOW DATA INVALID, IGNORE...";
                LOGGER.error(errMsg);
                System.out.println(errMsg);
                context.getCounter(Counter.LINESKIP).increment(1);
                return;
            } catch (Exception e) {
                // TODO: handle exception
                LOGGER.error(e);
                System.out.println(e);
                context.getCounter(Counter.LINESKIP).increment(1);
                return;
            }            
        }
    }
    
    public static class FlowSortReducer extends Reducer<FlowBean, NullWritable, 
        FlowBean, NullWritable> {
        @Override
        protected void reduce(
                FlowBean key,
                Iterable<NullWritable> values,
                Reducer<FlowBean, NullWritable, FlowBean, NullWritable>.Context context)
                throws IOException, InterruptedException {
            // TODO Auto-generated method stub
            //super.reduce(arg0, arg1, arg2);
            context.write(key, NullWritable.get());
        }
    }

    @Override
    public int run(String[] args) throws Exception {
        // TODO Auto-generated method stub
        String errMsg = "FlowSort: TEST STARTED...";
        LOGGER.debug(errMsg);
        System.out.println(errMsg);
        
        Configuration conf = new Configuration();
        //FOR Eclipse JVM Debug  
        //conf.set("mapreduce.job.jar", "flowsum.jar");
        Job job = Job.getInstance(conf);
        
        // JOB NAME
        job.setJobName("FlowSort");
        
        // JOB MAPPER & REDUCER
        job.setJarByClass(FlowSort.class);
        job.setMapperClass(FlowSortMapper.class);
        job.setReducerClass(FlowSortReducer.class);
        
        // MAP & REDUCE
        job.setOutputKeyClass(FlowBean.class);
        job.setOutputValueClass(NullWritable.class);
        // MAP
        job.setMapOutputKeyClass(FlowBean.class);
        job.setMapOutputValueClass(NullWritable.class);
        
        // JOB INPUT & OUTPUT PATH
        //FileInputFormat.addInputPath(job, new Path(args[0]));
        FileInputFormat.setInputPaths(job, args[1]);
        FileOutputFormat.setOutputPath(job, new Path(args[2]));
        
        // VERBOSE OUTPUT
        if (job.waitForCompletion(true)) {
            errMsg = "FlowSort: TEST SUCCESSFULLY...";
            LOGGER.debug(errMsg);
            System.out.println(errMsg);
            return 0;
        } else {
            errMsg = "FlowSort: TEST FAILED...";
            LOGGER.debug(errMsg);
            System.out.println(errMsg);
            return 1;
        }            
        
    }
    
    public static void main(String[] args) throws Exception {
        if (args.length != 3) {
            String errMsg = "FlowSort: ARGUMENTS ERROR";
            LOGGER.error(errMsg);
            System.out.println(errMsg);
            System.exit(-1);
        }
        
        int result = ToolRunner.run(new Configuration(), new FlowSort(), args);
        System.exit(result);
    }
}

2、参考资料：

Java异常处理：http://fluagen.blog.51cto.com/146595/304197

Hadoop获取出错行：http://www.aboutyun.com/thread-13962-1-1.html

http://blog.csdn.net/wuzhongju/article/details/8937893

http://blog.163.com/zhangxin0112zx@126/blog/static/161401319201501174156642/