hadoop mapreduce example

Package CN. LMJ. mapreduce; Import java. Io. ioexception; Import java. util. iterator; Import org. Apache. hadoop. fs. path; Import org. Apache. hadoop. Io. longwritable; Import org. Apache. hadoop. Io. text; Import org. Apache. hadoop. mapred. fileinputformat; Import or

Hadoop example code: 1. creatinga configuration object: to be able to read from or write to HDFS, you need tocreate a configuration object and pass configuration parameter to it usinghadoop configuration files. ImportOrg. Apache. hadoop. conf. configuration; ImportOrg. Apache. hadoop. fs. path; PublicClassMain { Publi

, the table will be recursive again. This is an example. It doesn't actually make any sense. It's just an example. Note that hbase locks are row-level locks. If you want to put the same row, it will not succeed. Observer is not easy to debug. Only a bunch of logs can be created ...... Package test. hbase. inaction. example5_2; import Java. io. ioexception; import Org. apache. commons. logging. log; import

Example of the hadoop configuration file automatically configured by shell [plain] #! /Bin/bash read-p 'Please input the directory of hadoop, ex:/usr/hadoop: 'hadoop_dir if [-d $ hadoop_dir]; then echo 'yes, this directory exist. 'else echo 'error, this directory not exist. 'Exit 1 fi if [-f $ hadoop_dir/conf/core-site

;ImportOrg.apache.hadoop.conf.Configuration;ImportOrg.apache.hadoop.io.Text;ImportOrg.apache.hadoop.ipc.RPC; Public class rpcclient { PrivateMyrpcprotocal protocal; Public rpcclient()throwsexception{inetsocketaddress address =NewInetsocketaddress ("localhost",9999); Protocal = (myrpcprotocal) rpc.waitforproxy (Myrpcprotocal.class,myrpcprotocal.versionid, address,NewConfiguration ());//rpc.setprotocolengine (New Configuration (), Myrpcprotocal.class, rpcengine.class);} Public void Pager(Strin

, exit.' exit 1 else if [ ! -d $hadoop_tmp_dir ];then echo 'The directory you have input is not exist , we will make it.' mkdir -p $hadoop_tmp_dir fi fi tmp_dir=$(echo $hadoop_tmp_dir|sed 's:/:\\/:g') sed -i "s/ip/$ip/g" $hadoop_dir/conf/core-site.xml sed -i "s/port/$port/g" $hadoop_dir/conf/core-site.xml sed -i "s/tmp_dir/$tmp_dir/g" $hadoop_dir/conf/core-site.xmlelse echo "The file $hadoop_dir/core-site.xml doen't exist." exit 1ficat $had

This "Hadoop Learning Notes" series is written on the basis of the hadoop:the definitive guide 3th with additional online data collection and a view of the Hadoop API plus your own hands-on understanding Focus on the features and functionality of Hadoop and other tools in the Hadoop biosphere (such as Pig,hive,hbase,av

serial number format for Hadoop. When you want to pass objects or persist objects between processes, you need the object serial number to be a byte stream, and then deserialize when you want to accept or read bytes from disk to the object.*/Private final static intwritable one = new intwritable (1);Private text Word = new text ();public void Map (Object key, Text value, context context)Throws IOException, Interruptedexception {StringTokenizer ITR = n

com.sun.tools.javac.Main wordcount.javajar CF wc.jar WordCount*. class4. Run the third step to build the Wc.jar package. It is important to note that the output folder is not created manually and is created automatically when the system is run.Bin/hadoop jar Wc.jar Wordcount/user/root/wordcount/input/user/root/wordcount/outputAt the end of normal operation, part-r-00000 and __success two files are generated under the output folder, where the analysis

Hadoop streaming example: $ {Hadoop_bin} streaming \ r -D mapred. Job. Name =$ {job_name} # Task Name -D stream. Memory. Limit = 1500 # Task memory limit -D mapred. Map. Capacity. Per. tasktracker = 1 \ r -D mapred. Reduce. Capacity. Per. tasktracker = 1 \ r -D mapred. Map. Tasks =$ {map_tasks} # map count -D mapred. Job. Map. Capacity =$ {map_capacity} # map capacity, which is generally consistent with t

(i) Download installation1. Download VISUALVMDownload on official website, with Mac version2, tools-Plug-ins, select the plug of interest to installAt this point, if there is a local running Java process, then the local there is already able to monitor the analysis(ii) Remote server configuration1, in any directory to establish the file Jstatd.all.policy, the contents are as follows:Grant CodeBase "file:${java.home}/. /lib/tools.jar "{Permission java.security.AllPermission;};2. Running Jstad Ser

, find out what we have in common, what the meeting map,shuffle,reduce do 2> What data we want, List 2. Where the implementation plan is noted 1> What separates the data and whether we need to customize the data type 2> roughly we need to filter out invalid records use custom data types to combine the fields we need and then accumulate (de-re-stage) the records according to the province 3> The data type can be undefined, use text to combine the field values and then