我有一个用管道（||）分隔的多行非结构化数据，如下所示：
||
nokia,111,55000,uk,20160809,109
100,online,credit,
10%,90%,2015
||
iphone,6,60000,USA,20160809,110,
100,online,credit
||
samsung,s7,60000,USA,20160809,110
100,online,credit
||
..... millions of records ....
第一条记录是3行，下一条记录是2行，所以行数不是常数。请告诉我如何使用Map Reduce 2处理此数据，自定义输入拆分＆amp;自定义记录阅读器任何链接＆amp;博客也很感激。
请告诉我以下Custom Record Reader课程中的任何错误：
public class CustomInputFormat extends FileInputFormat<LongWritable,Text>{
@Override
public RecordReader<LongWritable,Text> createRecordReader(InputSplit split,TaskAttemptContext context) {
return new CustomRecordReader();
}
public class CustomRecordReader extends RecordReader<LongWritable, Text> {
private long start;
private long pos;
private long end;
private LineReader in;
private int maxLineLength;
private LongWritable key = new LongWritable();
private Text value = new Text();
private static final Log LOG = LogFactory.getLog(CustomRecordReader.class);
@Override
public void initialize(InputSplit genericSplit, TaskAttemptContext context) throws IOException {
FileSplit split = (FileSplit) genericSplit;
Configuration job = context.getConfiguration();
this.maxLineLength = job.getInt("mapred.linerecordreader.maxlength",
Integer.MAX_VALUE);
start = split.getStart();
end = start + split.getLength();
final Path file = split.getPath();
FileSystem fs = file.getFileSystem(job);
FSDataInputStream fileIn = fs.open(split.getPath());
boolean skipFirstLine = false;
if (start != 0) {
skipFirstLine = true;
--start;
fileIn.seek(start);
}
in = new LineReader(fileIn, job);
if (skipFirstLine) {
Text dummy = new Text();
start += in.readLine(dummy, 0,
(int) Math.min((long) Integer.MAX_VALUE, end - start));
}
this.pos = start;
}
@Override
public boolean nextKeyValue() throws IOException {
int newSize = 0;
while (pos < end) {
newSize = in.readLine(value);
if (newSize == 0) break;
pos += newSize;
key.set(pos);
if(value.toString().equals("||"))
LOG.info("Skipped line of size " + newSize + " at pos "
+ (pos - newSize));
else
break;
}
if (newSize == 0)
return false;
return true;
}
@Override
public LongWritable getCurrentKey() throws IOException,
InterruptedException {
return key;
}
@Override
public Text getCurrentValue() throws IOException, InterruptedException {
return value;
}
@Override
public float getProgress() throws IOException, InterruptedException {
if (start == end) {
return 0.0f;
} else {
return Math.min(1.0f, (pos - start) / (float) (end - start));
}
}
@Override
public void close() throws IOException {
if (in != null) {
in.close();
}
}
}
public class CustomMapper extends Mapper<LongWritable, CustomInputFormat, LongWritable, CustomInputFormat>{
final static IntWritable one = new IntWritable(1);
@Override
protected void map(LongWritable key, CustomInputFormat value, org.apache.hadoop.mapreduce.Mapper.Context context) throws IOException, InterruptedException {
System.out.println(" *** Key is: "+key+" value is: "+value+" *** ");
if(null!=value ){
context.write(key, value);
}
}
}
public class CustomDriver extends Configured {
public static void main(String[] args) throws Exception {
if(args.length!=2){
System.out.println("pls give i/p & o/p direc");
System.exit(-1);
}
Job job = new Job();
job.setJarByClass(CustomDriver.class);
Configuration conf=job.getConfiguration();
FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
job.setMapperClass(CustomMapper.class);
job.setInputFormatClass(CustomInputFormat.class);
job.setMapOutputKeyClass(LongWritable.class);
job.setMapOutputValueClass(CustomInputFormat.class);
System.exit(job.waitForCompletion(true)?0:-1);
}
}
我在运行时遇到以下错误：
[cloudera@quickstart gous]$ hadoop jar c3.jar com.ownUnstruct.CustomDriver /user/mr/custom /user/mr/out
16/04/18 23:15:01 INFO client.RMProxy: Connecting to ResourceManager at /0.0.0.0:8032
16/04/18 23:15:02 WARN mapreduce.JobSubmitter: Hadoop command-line option parsing not performed. Implement the Tool interface and execute your application with ToolRunner to remedy this.
16/04/18 23:15:02 INFO input.FileInputFormat: Total input paths to process : 1
16/04/18 23:15:02 INFO mapreduce.JobSubmitter: number of splits:1
16/04/18 23:15:02 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1461045457615_0001
16/04/18 23:15:03 INFO impl.YarnClientImpl: Submitted application application_1461045457615_0001
16/04/18 23:15:03 INFO mapreduce.Job: The url to track the job: http://quickstart.cloudera:8088/proxy/application_1461045457615_0001/
16/04/18 23:15:03 INFO mapreduce.Job: Running job: job_1461045457615_0001
16/04/18 23:15:15 INFO mapreduce.Job: Job job_1461045457615_0001 running in uber mode : false
16/04/18 23:15:15 INFO mapreduce.Job: map 0% reduce 0%
16/04/18 23:15:22 INFO mapreduce.Job: Task Id : attempt_1461045457615_0001_m_000000_0, Status : FAILED
Error: java.io.IOException: Initialization of all the collectors failed. Error in last collector was :null
at org.apache.hadoop.mapred.MapTask.createSortingCollector(MapTask.java:414)
at org.apache.hadoop.mapred.MapTask.access$100(MapTask.java:81)
at org.apache.hadoop.mapred.MapTask$NewOutputCollector.<init>(MapTask.java:698)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:770)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:163)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1671)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:158)
Caused by: java.lang.NullPointerException
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.init(MapTask.java:1011)
at org.apache.hadoop.mapred.MapTask.createSortingCollector(MapTask.java:402)
... 9 more
答案 0 :(得分：0)
假设管道符号总是在换行符前面跟后面，我认为不需要自定义输入拆分或自定义记录阅读器。您可以按如下方式编写映射器的代码：
var rightNow = DateTime.Now;
dateTimePicker1.Value = new DateTime(rightNow.Year, rightNow.Month, rightNow.Day);
这可以帮助您开始处理。
更新：将public class MyMapper extends Mapper<LongWritable, Text, Text, Text> {
private Text textValue;
@Override
public void map(LongWritable key, Text value, Context context)
throws IOException, InterruptedException {
//process the data
}
@Override
public void run(Mapper<LongWritable, Text, Text, Text>.Context context)
throws IOException, InterruptedException {
setup(context);
textValue = new Text();
StringBuffer sb = new StringBuffer();
while (context.nextKeyValue()) {
String line = context.getCurrentValue().toString();
if(line.equals("||")){
textValue.set(sb.toString());
if(!("".equals(sb.toString())))
map(context.getCurrentKey(), textValue, context);
sb = new StringBuffer();
} else {
sb.append(line);
}
}
cleanup(context);
}
}
中的代码更改为类似内容，然后尝试一下。
nextKeyValue()更新：将映射器更改为以下内容：
@Override
public boolean nextKeyValue() throws IOException {
int newSize = 0;
StringBuffer sb = new StringBuffer();
while (pos < end) {
newSize = in.readLine(value);
if (newSize == 0) break;
pos += newSize;
key.set(pos);
if(value.toString().equals("||")){
LOG.info("Skipped line of size " + newSize + " at pos "
+ (pos - newSize));
break;
} else
sb.append(value.toString());
}
value.set(sb.toString());
if (newSize == 0)
return false;
return true;
}
在public class CustomMapper extends Mapper<LongWritable, Text, LongWritable, Text>{
@Override
protected void map(LongWritable key, Text value, Context context)
throws IOException, InterruptedException {
System.out.println(" *** Key is: "+key+" value is: "+value+" *** ");
if(null!=value ){
context.write(key, value);
}
}
}
课程中，更改以下行
CustomDriver到
job.setMapOutputValueClass(CustomInputFormat.class);