hadoop样例程序

     2013年04月09日       teddy.sun       运维笔记->Hadoop       hadoop example 

Hadoop集群搭建好以后,我们可以用hadoop example测试一下集群是否已经可以正常工作了。
hadoop example程序在hadoop发行版本根目录下,如hadoop-examples-0.20.2-cdh3u4.jar
执行hadoop jar hadoop-examples-0.20.2-cdh3u4.jar可以看到所有样例程序:
An example program must be given as the first argument.
Valid program names are:
  aggregatewordcount: An Aggregate based map/reduce program that counts the words in the input files.
  aggregatewordhist: An Aggregate based map/reduce program that computes the histogram of the words in the input files.
  dbcount: An example job that count the pageview counts from a database.
  grep: A map/reduce program that counts the matches of a regex in the input.
  join: A job that effects a join over sorted, equally partitioned datasets
  multifilewc: A job that counts words from several files.
  pentomino: A map/reduce tile laying program to find solutions to pentomino problems.
  pi: A map/reduce program that estimates Pi using monte-carlo method.
  randomtextwriter: A map/reduce program that writes 10GB of random textual data per node.
  randomwriter: A map/reduce program that writes 10GB of random data per node.
  secondarysort: An example defining a secondary sort to the reduce.
  sleep: A job that sleeps at each map and reduce task.
  sort: A map/reduce program that sorts the data written by the random writer.
  sudoku: A sudoku solver.
  teragen: Generate data for the terasort
  terasort: Run the terasort
  teravalidate: Checking results of terasort
  wordcount: A map/reduce program that counts the words in the input files.
A.用hadoop来算个PI
hadoop jar hadoop-examples-0.20.2-cdh3u4.jar pi 100 100