本文介绍Hadoop- The Definitive Guide一书中的NCDC数据准备,为后面的学习构建大数据环境;
环境
3节点 Hadoop 2.7.3 集群; java version "1.8.0_111"
1 下载数据
从NCDC下载20,21世纪天历史气数据;官网按年份命名文件夹,每个文件内包含N个gz打包的(*.op.gz)全年各地区天气数据文件和一个全年天气数据打包tar文件,比如1971年;
034700-99999-1971.op.gz
035623-99999-1971.op.gz
035833-99999-1971.op.gz
035963-99999-1971.op.gz
036880-99999-1971.op.gz
040180-16201-1971.op.gz
061800-99999-1971.op.gz
080870-99999-1971.op.gz
gsod_1971.tar
*1971.op.gz就是该年的某地区某天数据打包,而*1971.tar就是对全年*.op.gz文件的打包;只需要下载tar文件,再解压即可得到全年天气数据;在这里下载从1902年到2017年tar文件;
#!/bin/bash
for i in {1902..2017}
do
cd /home/lanstonwu/hapood/ncdc
wget --execute robots=off -r -np -nH --cut-dirs=4 -R index.html* ftp://ftp.ncdc.noaa.gov/pub/data/gsod/$i/*.tar
done
2 上传数据
为了便于使用,文件下载完成后,推荐使用hadoop将全年的天气数据合并为一个文件;由于下载的数据保存在本地,为了使用hadoop并行处理这些数据,需要将数据上传到HDFS;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URI;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;
/**
* 将本地文件上传到hadoop集群 hdfs 提示权限不足时设置环境变量export HADOOP_USER_NAME=hadoop再运行
*
* @author lanstonwu
*
*/
public class UpLoadFile {
public static void main(String[] args) throws IOException {
// hdfs目录
String target = "hdfs://192.168.56.12:9000/gsod";
// 本地文件目录
File file = new File("/home/lanstonwu/hapood/ncdc");
if (file.exists()) {
File[] files = file.listFiles();
if (files.length == 0) {
System.out.println("文件夹是空的!");
return;
} else {
for (File file2 : files) {// 遍历本地文件目录
if (file2.isDirectory()) {
System.out.println("文件夹:" + file2.getAbsolutePath() + "," + file2.getName());
} else {
System.out.println("文件:" + file2.getAbsolutePath() + ",name:" + file2.getName());
// 读取本地文件
FileInputStream fis = new FileInputStream(new File(file2.getAbsolutePath()));
Configuration config = new Configuration();
// Returns the FileSystem for this URI's scheme and authority
FileSystem fs = FileSystem.get(URI.create(target + "/" + file2.getName()), config);
// Create an FSDataOutputStream at the indicated Path
OutputStream os = fs.create(new Path(target + "/" + file2.getName()));
// 复制数据
IOUtils.copyBytes(fis, os, 4096, true);
System.out.println("拷贝完成...");
}
}
}
} else {
System.out.println("文件不存在!");
}
}
}
3 合并数据
由于hadoop处理大数据文件比处理小数据文件更有优势,这里将tar文件内的全年gz打包数据合并为一个文件;因为仅仅合并数据,用map即可,无需reduce,用hadoop的streaming并行完成这个工作;首先准备处理文件清单;
$ vi ncdc_file_list.txt
hdfs://gp-sdw1:9000/gsod/gsod_1981.tar
hdfs://gp-sdw1:9000/gsod/gsod_1977.tar
hdfs://gp-sdw1:9000/gsod/gsod_1978.tar
hdfs://gp-sdw1:9000/gsod/gsod_1979.tar
hdfs://gp-sdw1:9000/gsod/gsod_1980.tar
hdfs://gp-sdw1:9000/gsod/gsod_1981.tar
hdfs://gp-sdw1:9000/gsod/gsod_1982.tar
hdfs://gp-sdw1:9000/gsod/gsod_1983.tar
.....
文件清单中记录所有要处理的文件,每一行即代表一个文件,hadoop streaming逐行读取传递给map函数处理;接着编写map脚本,每一个步骤有序号和说明;
#!/bin/bash
HADOOP_HOME=/opt/hadoop/2.7.3
cd /tmp
#1 NLineInputFormat give a signle line:offset is key,hdfile is HDFS
read offset hdfile
#2 restrive file from hdfs
echo "reporter:status:Restrivering $hdfile" >&2
$HADOOP_HOME/bin/hadoop fs -get $hdfile .
#3 get short name from tar file
target=`basename $hdfile .tar`
#4 create directory by name of target
mkdir $target
#5 un-tar the local file to target directory
tar xvf `basename $hdfile` -C $target
#6 un-zip the local file and merge them to one file
echo "reporter:status:Un-gzipping $target" >&2
for file in $target/*
do
gunzip -c $file>>$target.all
echo "repoter:status:Processed $file" >&2
done
#7 Put gzipped version into HDFS
echo "reporter:status:Gzipping $target and putting in HDFS" >&2
gzip -c $target.all | $HADOOP_HOME/bin/hadoop fs -put - /ncdc_year_gz/$target.gz
#8 remove the local file
rm -Rf $target
rm -f $target.all
rm -f $target.tar
hadoop从HDFS中读取文件到本地(第2步),获取文件名(第3步),根据获取到的文件名创建目录(第4步),解压该年的全年数据到目录里(第5步),循环解压和读取全年数据合并到一个文件里(第6步),将合并的文件压缩并上传到HDFS ncdc_year_gz目录(第7步),删除本地文件目录和文件(第8步).reporter 的目的是返回状态信息,便于监控mapper运行.注意:必须设置HADOOP_HOME变量,如果不设置该变量,所有调用hadoop的地方必须全路径,因为在运行时操作系统上配置的HADOOP_HOME变量是不可见,会导致运行报如下错误;
No such file or directory
PipeMapRed.waitOutputThreads(): subprocess failed with code 127
1.4 运行mapper 将准备好的NCDC文件清单上传到HDFS(hadoop集群节点需要);
$ hadoop fs -put ncdc_file_list.txt /
运行map;
hadoop jar $HADOOP_HOME/share/hadoop/tools/lib/hadoop-streaming-*.jar
-D mapred.reduce.tasks=0
-D mapred.map.tasks.speculative.execution=false
-D mapred.task.timeout=12000000
-input /ncdc_file_list.txt
-inputformat org.apache.hadoop.mapred.lib.NLineInputFormat
-output output
-mapper load_ncdc_map.sh
-file /home/hadoop/script/load_ncdc_map.sh
禁用reduce,设置超时,设置input为准备好的ncdc清单文件,设置mapper和file为map脚本.
17/10/01 13:05:36 WARN streaming.StreamJob: -file option is deprecated, please use generic option -files instead.
packageJobJar: [/home/hadoop/script/load_ncdc_map.sh, /tmp/hadoop-unjar708897410907700502/] [] /tmp/streamjob2755689666173396550.jar tmpDir=null
17/10/01 13:05:37 INFO client.RMProxy: Connecting to ResourceManager at gp-sdw1/192.168.56.12:8032
17/10/01 13:05:37 INFO client.RMProxy: Connecting to ResourceManager at gp-sdw1/192.168.56.12:8032
17/10/01 13:05:38 INFO mapred.FileInputFormat: Total input paths to process : 1
17/10/01 13:05:38 INFO mapreduce.JobSubmitter: number of splits:114
17/10/01 13:05:38 INFO Configuration.deprecation: mapred.reduce.tasks is deprecated. Instead, use mapreduce.job.reduces
17/10/01 13:05:38 INFO Configuration.deprecation: mapred.map.tasks.speculative.execution is deprecated. Instead, use mapreduce.map.speculative
17/10/01 13:05:38 INFO Configuration.deprecation: mapred.task.timeout is deprecated. Instead, use mapreduce.task.timeout
17/10/01 13:05:38 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1506832924184_0001
17/10/01 13:05:39 INFO impl.YarnClientImpl: Submitted application application_1506832924184_0001
17/10/01 13:05:39 INFO mapreduce.Job: The url to track the job: http://gp-sdw1:8088/proxy/application_1506832924184_0001/
17/10/01 13:05:39 INFO mapreduce.Job: Running job: job_1506832924184_0001
17/10/01 13:05:46 INFO mapreduce.Job: Job job_1506832924184_0001 running in uber mode : false
17/10/01 13:05:46 INFO mapreduce.Job: map 0% reduce 0%
17/10/01 13:06:00 INFO mapreduce.Job: map 1% reduce 0%
17/10/01 13:06:04 INFO mapreduce.Job: map 2% reduce 0%
17/10/01 13:06:09 INFO mapreduce.Job: map 3% reduce 0%
17/10/01 13:06:12 INFO mapreduce.Job: map 4% reduce 0%
17/10/01 13:06:17 INFO mapreduce.Job: map 5% reduce 0%
17/10/01 13:06:23 INFO mapreduce.Job: map 6% reduce 0%
17/10/01 13:06:25 INFO mapreduce.Job: map 7% reduce 0%
17/10/01 13:06:28 INFO mapreduce.Job: map 11% reduce 0%
17/10/01 13:06:32 INFO mapreduce.Job: map 12% reduce 0%
17/10/01 13:06:34 INFO mapreduce.Job: map 13% reduce 0%
17/10/01 13:06:37 INFO mapreduce.Job: map 14% reduce 0%
17/10/01 13:06:38 INFO mapreduce.Job: map 17% reduce 0%
17/10/01 13:06:39 INFO mapreduce.Job: map 19% reduce 0%
17/10/01 13:06:56 INFO mapreduce.Job: map 20% reduce 0%
17/10/01 13:07:02 INFO mapreduce.Job: map 21% reduce 0%
17/10/01 13:07:12 INFO mapreduce.Job: map 22% reduce 0%
17/10/01 13:07:14 INFO mapreduce.Job: map 23% reduce 0%
17/10/01 13:07:16 INFO mapreduce.Job: map 24% reduce 0%
17/10/01 13:07:17 INFO mapreduce.Job: map 25% reduce 0%
17/10/01 13:07:52 INFO mapreduce.Job: map 27% reduce 0%
Status即为map脚本reporter返回信息;map完成,检查hadoop 合并后的文件;
$ hadoop fs -ls /ncdc_year_gz
-rw-r--r-- 3 hadoop supergroup 14809707 2017-10-01 13:11 /ncdc_year_gz/gsod_1966.gz
-rw-r--r-- 3 hadoop supergroup 14771822 2017-10-01 13:13 /ncdc_year_gz/gsod_1967.gz
-rw-r--r-- 3 hadoop supergroup 13592592 2017-10-01 13:12 /ncdc_year_gz/gsod_1968.gz
-rw-r--r-- 3 hadoop supergroup 20475061 2017-10-01 13:14 /ncdc_year_gz/gsod_1969.gz
-rw-r--r-- 3 hadoop supergroup 20012492 2017-10-01 13:14 /ncdc_year_gz/gsod_1970.gz
-rw-r--r-- 3 hadoop supergroup 11205341 2017-10-01 13:12 /ncdc_year_gz/gsod_1971.gz
-rw-r--r-- 3 hadoop supergroup 4556815 2017-10-01 13:11 /ncdc_year_gz/gsod_1972.gz
-rw-r--r-- 3 hadoop supergroup 21961972 2017-10-01 13:18 /ncdc_year_gz/gsod_1974.gz
-rw-r--r-- 3 hadoop supergroup 23030229 2017-10-01 13:18 /ncdc_year_gz/gsod_1976.gz
-rw-r--r-- 3 hadoop supergroup 23293175 2017-10-01 13:18 /ncdc_year_gz/gsod_1978.gz
-rw-r--r-- 3 hadoop supergroup 24564712 2017-10-01 13:18 /ncdc_year_gz/gsod_1980.gz
-rw-r--r-- 3 hadoop supergroup 29662599 2017-10-01 13:19 /ncdc_year_gz/gsod_1988.gz
-rw-r--r-- 3 hadoop supergroup 29092407 2017-10-01 13:19 /ncdc_year_gz/gsod_1993.gz
-rw-r--r-- 3 hadoop supergroup 25363736 2017-10-01 13:19 /ncdc_year_gz/gsod_1994.gz
-rw-r--r-- 3 hadoop supergroup 22179093 2017-10-01 13:19 /ncdc_year_gz/gsod_1995.gz