2010-05-10

• 測試 ​A MapReduce Algorithm for Matrix Multiplication 所提供之矩陣相乘範例
  • 發現會有 IOException 錯誤訊息，肇因於 /tmp/MatrixMultiply/out/_logs 是目錄而不是檔案

    10/05/10 15:23:23 INFO input.FileInputFormat: Total input paths to process : 1
    10/05/10 15:23:23 INFO mapred.JobClient: Running job: job_201005101012_0016
    10/05/10 15:23:24 INFO mapred.JobClient:  map 0% reduce 0%
    10/05/10 15:23:33 INFO mapred.JobClient:  map 100% reduce 0%
    10/05/10 15:23:45 INFO mapred.JobClient:  map 100% reduce 100%
    10/05/10 15:23:47 INFO mapred.JobClient: Job complete: job_201005101012_0016
    ..........
    Exception in thread "main" java.io.IOException: Cannot open filename /tmp/MatrixMultiply/out/_logs
            at org.apache.hadoop.hdfs.DFSClient$DFSInputStream.openInfo(DFSClient.java:1497)
    

  • [解法]

    jazz@drbl:~/hadoop-0.20.2$ wget http://trac.nchc.org.tw/cloud/raw-attachment/wiki/jazz/10-05-10/matrix.tar.gz
    jazz@drbl:~/hadoop-0.20.2$ tar zxvf matrix.tar.gz
    jazz@drbl:~/hadoop-0.20.2$ cd matrix/
    jazz@drbl:~/hadoop-0.20.2/matrix$ ant
    jazz@drbl:~/hadoop-0.20.2/matrix$ mv matrix.jar ../.
    jazz@drbl:~/hadoop-0.20.2/matrix$ cd ..
    jazz@drbl:~/hadoop-0.20.2$ bin/hadoop jar matrix.jar TestMatrixMultiply