问题
I am trying to write a snappy block compressed sequence file from a map-reduce job. I am using hadoop 2.0.0-cdh4.5.0, and snappy-java 1.0.4.1
Here is my code:
package jinvestor.jhouse.mr;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.List;
import jinvestor.jhouse.core.House;
import jinvestor.jhouse.core.util.HouseAvroUtil;
import jinvestor.jhouse.download.HBaseHouseDAO;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.LocatedFileStatus;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.RemoteIterator;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
import org.apache.hadoop.hbase.mapreduce.TableMapper;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.SequenceFile;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.SnappyCodec;
import org.apache.hadoop.mapred.FileOutputFormat;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat;
import org.apache.hadoop.mapreduce.Job;
import org.apache.mahout.math.DenseVector;
import org.apache.mahout.math.NamedVector;
import org.apache.mahout.math.VectorWritable;
/**
* Produces mahout vectors from House entries in HBase.
*
* @author Michael Scott Knapp
*
*/
public class HouseVectorizer {
private final Configuration configuration;
private final House minimumHouse;
private final House maximumHouse;
public HouseVectorizer(final Configuration configuration,
final House minimumHouse, final House maximumHouse) {
this.configuration = configuration;
this.minimumHouse = minimumHouse;
this.maximumHouse = maximumHouse;
}
public void vectorize() throws IOException, ClassNotFoundException, InterruptedException {
JobConf jobConf = new JobConf();
jobConf.setMapOutputKeyClass(LongWritable.class);
jobConf.setMapOutputValueClass(VectorWritable.class);
// we want the vectors written straight to HDFS,
// the order does not matter.
jobConf.setNumReduceTasks(0);
Path outputDir = new Path("/home/cloudera/house_vectors");
FileSystem fs = FileSystem.get(configuration);
if (fs.exists(outputDir)) {
fs.delete(outputDir, true);
}
FileOutputFormat.setOutputPath(jobConf, outputDir);
// I want the mappers to know the max and min value
// so they can normalize the data.
// I will add them as properties in the configuration,
// by serializing them with avro.
String minmax = HouseAvroUtil.toBase64String(Arrays.asList(minimumHouse,
maximumHouse));
jobConf.set("minmax", minmax);
Job job = Job.getInstance(jobConf);
Scan scan = new Scan();
scan.addFamily(Bytes.toBytes("data"));
TableMapReduceUtil.initTableMapperJob("homes", scan,
HouseVectorizingMapper.class, LongWritable.class,
VectorWritable.class, job);
job.setOutputFormatClass(SequenceFileOutputFormat.class);
job.setOutputKeyClass(LongWritable.class);
job.setOutputValueClass(VectorWritable.class);
job.setMapOutputKeyClass(LongWritable.class);
job.setMapOutputValueClass(VectorWritable.class);
SequenceFileOutputFormat.setOutputCompressionType(job, SequenceFile.CompressionType.BLOCK);
SequenceFileOutputFormat.setOutputCompressorClass(job, SnappyCodec.class);
SequenceFileOutputFormat.setOutputPath(job, outputDir);
job.getConfiguration().setClass("mapreduce.map.output.compress.codec",
SnappyCodec.class,
CompressionCodec.class);
job.waitForCompletion(true);
}
When I run it I get this:
java.lang.Exception: java.lang.UnsatisfiedLinkError: org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy()Z
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:401)
Caused by: java.lang.UnsatisfiedLinkError: org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy()Z
at org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy(Native Method)
at org.apache.hadoop.io.compress.SnappyCodec.checkNativeCodeLoaded(SnappyCodec.java:62)
at org.apache.hadoop.io.compress.SnappyCodec.getCompressorType(SnappyCodec.java:127)
at org.apache.hadoop.io.compress.CodecPool.getCompressor(CodecPool.java:104)
at org.apache.hadoop.io.compress.CodecPool.getCompressor(CodecPool.java:118)
at org.apache.hadoop.io.SequenceFile$Writer.init(SequenceFile.java:1169)
at org.apache.hadoop.io.SequenceFile$Writer.<init>(SequenceFile.java:1080)
at org.apache.hadoop.io.SequenceFile$BlockCompressWriter.<init>(SequenceFile.java:1400)
at org.apache.hadoop.io.SequenceFile.createWriter(SequenceFile.java:274)
at org.apache.hadoop.io.SequenceFile.createWriter(SequenceFile.java:527)
at org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat.getSequenceWriter(SequenceFileOutputFormat.java:64)
at org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat.getRecordWriter(SequenceFileOutputFormat.java:75)
at org.apache.hadoop.mapred.MapTask$NewDirectOutputCollector.<init>(MapTask.java:617)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:737)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:338)
at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:233)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
If I comment out these lines then my test passes:
SequenceFileOutputFormat.setOutputCompressionType(job, SequenceFile.CompressionType.BLOCK);
SequenceFileOutputFormat.setOutputCompressorClass(job, SnappyCodec.class);
job.getConfiguration().setClass("mapreduce.map.output.compress.coded",
SnappyCodec.class,
CompressionCodec.class);
However, I really want to use snappy compression in my sequence files. Can somebody please explain to me what I am doing wrong?
回答1:
Found the following information from the Cloudera Communities
- Ensure that LD_LIBRARY_PATH and JAVA_LIBRARY_PATH contains the native directory path having the libsnappy.so** files.
- Ensure that LD_LIBRARY_PATH and JAVA_LIBRARY path have been exported in the SPARK environment(spark-env.sh).
For example I use Hortonworks HDP and I have the following configuration in my spark-env.sh
export JAVA_LIBRARY_PATH=$JAVA_LIBRARY_PATH:/usr/hdp/2.2.0.0-2041/hadoop/lib/native
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/hdp/2.2.0.0-2041/hadoop/lib/native
export SPARK_YARN_USER_ENV="JAVA_LIBRARY_PATH=$JAVA_LIBRARY_PATH,LD_LIBRARY_PATH=$LD_LIBRARY_PATH"
回答2:
check your core-site.xml and mapred-site.xml they should contain correct properties and path of the folder with libraries
core-site.xml
<property>
<name>io.compression.codecs</name>
<value>org.apache.hadoop.io.compress.GzipCodec,org.apache.hadoop.io.compress.DefaultCodec,org.apache.hadoop.io.compress.SnappyCodec</value>
</property>
mapred-site.xml
<property>
<name>mapreduce.map.output.compress</name>
<value>true</value>
</property>
<property>
<name>mapred.map.output.compress.codec</name>
<value>org.apache.hadoop.io.compress.SnappyCodec</value>
</property>
<property>
<name>mapreduce.admin.user.env</name>
<value>LD_LIBRARY_PATH=/usr/hdp/2.2.0.0-1084/hadoop/lib/native</value>
</property>
LD_LIBRARY_PATH - has to contain path of libsnappy.so .
回答3:
My problem was that my JRE did not contain the appropriate native libraries. This may or may not be because I switched the JDK from cloudera's pre-built VM to JDK 1.7. The snappy .so files are in your hadoop/lib/native directory, the JRE needs to have them. Adding them to the classpath did not seem to resolve my issue. I resolved it like this:
$ cd /usr/lib/hadoop/lib/native
$ sudo cp *.so /usr/java/latest/jre/lib/amd64/
Then I was able to use the SnappyCodec class. Your paths may be different though.
That seemed to get me to the next problem:
Caused by: java.lang.RuntimeException: native snappy library not available: SnappyCompressor has not been loaded.
Still trying to resolve that.
回答4:
I you need all files, not only the *.so ones. Also ideally you would include the folder to your path instead of copying the libs from there. You need to restart the MapReduce service after this, so that the new libraries are taken and can be used.
Niko
回答5:
after removing hadoop.dll (which i copied manually) from windows\system32 and setting up HADOOP_HOME=\hadoop-2.6.4 IT WORKS!!!
回答6:
In my case, you may check the hive-conf files : mapred-site.xml , and check the key: mapreduce.admin.user.env 's value,
I tested it in a new datanode, and received unlinked-buildSnappy error on the machine where is no native dependencies ( libsnappy.so , etc)
来源：https://stackoverflow.com/questions/22150417/hadoop-mapreduce-java-lang-unsatisfiedlinkerror-org-apache-hadoop-util-nativec