Hadoop 修改Grep以解析序列/快照文件
我试图将Grep示例与CDH捆绑在一起,以读取序列/快照文件 默认情况下,程序在尝试读取序列/快照文件时抛出错误: java.io.EOFException:输入流中块的意外结束 位于org.apache.hadoop.io.compress.BlockDecompressorStream.getCompressedData(BlockDecompressorStream.java:121)Hadoop 修改Grep以解析序列/快照文件,hadoop,mapreduce,grep,sequence,snappy,Hadoop,Mapreduce,Grep,Sequence,Snappy,我试图将Grep示例与CDH捆绑在一起,以读取序列/快照文件 默认情况下,程序在尝试读取序列/快照文件时抛出错误: java.io.EOFException:输入流中块的意外结束 位于org.apache.hadoop.io.compress.BlockDecompressorStream.getCompressedData(BlockDecompressorStream.java:121) 位于org.apache.hadoop.io.compress.BlockDecompressorStr
位于org.apache.hadoop.io.compress.BlockDecompressorStream.decompress(BlockDecompressorStream.java:95)
位于org.apache.hadoop.io.compress.DecompressorStream.read(DecompressorStream.java:83)
读取(InputStream.java:82) 所以我编辑了代码来读取序列文件 更改:
FileInputFormat.setInputPaths(grepJob, args[0]);
致:
但我还是犯了同样的错误
1) 我需要手动设置输入压缩编解码器吗?我以为SequenceFile阅读器会自动检测压缩。2) 如果我需要手动设置压缩,是使用“setInputFormatClass”还是在“conf”对象中设置的?让代码正常工作。我有点困惑,但我不必在代码中的任何地方指定压缩编解码器。以下是原始代码:
package org.myorg;
import java.util.Random;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.map.InverseMapper;
import org.apache.hadoop.mapreduce.lib.map.RegexMapper;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.mapreduce.lib.reduce.LongSumReducer;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.hadoop.io.SequenceFile.CompressionType;
import org.apache.hadoop.io.SequenceFile.Metadata;
import org.apache.hadoop.io.compress.*;
/* Extracts matching regexs from input files and counts them. */
public class Grep extends Configured implements Tool {
private Grep() {} // singleton
public int run(String[] args) throws Exception {
if (args.length < 3) {
System.out.println("Grep <inDir> <outDir> <regex> [<group>]");
ToolRunner.printGenericCommandUsage(System.out);
return 2;
}
Path tempDir =
new Path("grep-temp-"+
Integer.toString(new Random().nextInt(Integer.MAX_VALUE)));
Configuration conf = getConf();
conf.set(RegexMapper.PATTERN, args[2]);
if (args.length == 4)
conf.set(RegexMapper.GROUP, args[3]);
Job grepJob = new Job(conf);
try {
grepJob.setJobName("grep-search");
FileInputFormat.setInputPaths(grepJob, args[0]);
grepJob.setInputFormatClass(SequenceFileAsTextInputFormat.class);
grepJob.setMapperClass(RegexMapper.class);
grepJob.setCombinerClass(LongSumReducer.class);
grepJob.setReducerClass(LongSumReducer.class);
FileOutputFormat.setOutputPath(grepJob, tempDir);
grepJob.setOutputFormatClass(SequenceFileOutputFormat.class);
grepJob.setOutputKeyClass(Text.class);
grepJob.setOutputValueClass(LongWritable.class);
grepJob.waitForCompletion(true);
Job sortJob = new Job(conf);
sortJob.setJobName("grep-sort");
FileInputFormat.setInputPaths(sortJob, tempDir);
sortJob.setInputFormatClass(SequenceFileInputFormat.class);
sortJob.setMapperClass(InverseMapper.class);
sortJob.setNumReduceTasks(1); // write a single file
FileOutputFormat.setOutputPath(sortJob, new Path(args[1]));
sortJob.setSortComparatorClass( // sort by decreasing freq
LongWritable.DecreasingComparator.class);
sortJob.waitForCompletion(true);
}
finally {
FileSystem.get(conf).delete(tempDir, true);
}
return 0;
}
public static void main(String[] args) throws Exception {
int res = ToolRunner.run(new Configuration(), new Grep(), args);
System.exit(res);
}
}
package org.myorg;
import java.util.Random;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configured;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
import org.apache.hadoop.mapreduce.lib.map.InverseMapper;
import org.apache.hadoop.mapreduce.lib.map.RegexMapper;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.mapreduce.lib.reduce.LongSumReducer;
import org.apache.hadoop.util.Tool;
import org.apache.hadoop.util.ToolRunner;
import org.apache.hadoop.io.SequenceFile.CompressionType;
import org.apache.hadoop.io.SequenceFile.Metadata;
import org.apache.hadoop.io.compress.*;
/* Extracts matching regexs from input files and counts them. */
public class Grep extends Configured implements Tool {
private Grep() {} // singleton
public int run(String[] args) throws Exception {
if (args.length < 3) {
System.out.println("Grep <inDir> <outDir> <regex> [<group>]");
ToolRunner.printGenericCommandUsage(System.out);
return 2;
}
Path tempDir =
new Path("grep-temp-"+
Integer.toString(new Random().nextInt(Integer.MAX_VALUE)));
Configuration conf = getConf();
conf.set(RegexMapper.PATTERN, args[2]);
if (args.length == 4)
conf.set(RegexMapper.GROUP, args[3]);
Job grepJob = new Job(conf);
try {
grepJob.setJobName("grep-search");
FileInputFormat.setInputPaths(grepJob, args[0]);
grepJob.setInputFormatClass(SequenceFileAsTextInputFormat.class);
grepJob.setMapperClass(RegexMapper.class);
grepJob.setCombinerClass(LongSumReducer.class);
grepJob.setReducerClass(LongSumReducer.class);
FileOutputFormat.setOutputPath(grepJob, tempDir);
grepJob.setOutputFormatClass(SequenceFileOutputFormat.class);
grepJob.setOutputKeyClass(Text.class);
grepJob.setOutputValueClass(LongWritable.class);
grepJob.waitForCompletion(true);
Job sortJob = new Job(conf);
sortJob.setJobName("grep-sort");
FileInputFormat.setInputPaths(sortJob, tempDir);
sortJob.setInputFormatClass(SequenceFileInputFormat.class);
sortJob.setMapperClass(InverseMapper.class);
sortJob.setNumReduceTasks(1); // write a single file
FileOutputFormat.setOutputPath(sortJob, new Path(args[1]));
sortJob.setSortComparatorClass( // sort by decreasing freq
LongWritable.DecreasingComparator.class);
sortJob.waitForCompletion(true);
}
finally {
FileSystem.get(conf).delete(tempDir, true);
}
return 0;
}
public static void main(String[] args) throws Exception {
int res = ToolRunner.run(new Configuration(), new Grep(), args);
System.exit(res);
}
}
package org.myorg;
import java.io.*;
import java.util.*;
import java.net.*;
import org.apache.hadoop.fs.*;
import org.apache.hadoop.conf.*;
import org.apache.hadoop.io.*;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.util.*;
import org.apache.hadoop.io.SequenceFile.CompressionType;
import org.apache.hadoop.io.SequenceFile.Metadata;
import org.apache.hadoop.io.compress.*;
import java.nio.charset.*;
public class seqcat {
public static void main(String[] args) throws IOException {
String uri = args[0];
Configuration conf = new Configuration();
FileSystem fs = FileSystem.getLocal(conf);
Path seqFilePath = new Path(uri);
SequenceFile.Reader reader = new SequenceFile.Reader(conf, SequenceFile.Reader.file(seqFilePath));
Writable key = (Writable) ReflectionUtils.newInstance(reader.getKeyClass(), conf);
Writable value = (Writable) ReflectionUtils.newInstance(reader.getValueClass(), conf);
CompressionCodecFactory ccf = new CompressionCodecFactory(conf);
CompressionCodec codec = ccf.getCodecByClassName(DefaultCodec.class.getName());
while (reader.next(key, value)) {
byte[] strBytes = ((BytesWritable) value).getBytes();
int len = ((BytesWritable) value).getLength();
String val = new String(strBytes,0,len,Charset.forName("UTF-8"));
System.out.println(val);
}
reader.close();
}
}