java - Why Map record output=0 , even when I am giving output in mapper -

i have tried lot , not understanding reason why mapper record output =0 . want mapper read lines more once working on big data , need data on each line more once trying first small file(graph.txt) contain --

   1,2,4,6    2,10,3,7    3,6,5,8    4,7,7,9    5,13,9,9   

but mapper deal file line line there no other way first store values in file when map() method called first (n-1) times , processing in last map() method call. each row in file storing data in row array. , in last map method call giving output via output.collect() function. using setup() method calculate no. of rows in file ,as setup() called once each mapper. here as input file small 1 mapper called.

i stuck @ while , new , please give solution. in advance. here's code.

driver code-

    import org.apache.hadoop.fs.path;     import org.apache.hadoop.io.text;     import org.apache.hadoop.mapred.fileinputformat;     import org.apache.hadoop.mapred.fileoutputformat;     import org.apache.hadoop.mapred.jobclient;     import org.apache.hadoop.mapred.jobconf;     import org.apache.hadoop.mapred.textinputformat;     import org.apache.hadoop.mapred.textoutputformat;       public class primdriver {     public static void main(string[] args) throws exception {         jobconf conf = new jobconf(primdriver.class);         conf.setjobname("primdriver");          conf.setoutputkeyclass(text.class);         conf.setoutputvalueclass(text.class);          conf.setmapperclass(primmapper.class);         //conf.setcombinerclass(reduce.class);         conf.setreducerclass(primreducer.class);          conf.setinputformat(textinputformat.class);         conf.setoutputformat(textoutputformat.class);          fileinputformat.setinputpaths(conf, new path(args[0]));         fileoutputformat.setoutputpath(conf, new path(args[1]));         jobclient.runjob(conf);       } } 

mapper code -

    import java.io.bufferedreader;     import java.io.ioexception;     import java.io.inputstreamreader;      import org.apache.hadoop.conf.configuration;     import org.apache.hadoop.fs.filesystem;     import org.apache.hadoop.fs.path;     import org.apache.hadoop.io.longwritable;     import org.apache.hadoop.io.text;     import org.apache.hadoop.mapred.mapreducebase;     import org.apache.hadoop.mapred.mapper;     import org.apache.hadoop.mapred.outputcollector;     import org.apache.hadoop.mapred.reporter;     import org.apache.hadoop.mapreduce.mapper.context;      public class primmapper extends mapreducebase implements              mapper<longwritable, text, text, text> {         //private final static intwritable 1 = new intwritable(1);         //private text word = new text();         private int no_line=0;         private int i=0;         public void setup(context context) throws ioexception{             path pt=new path("hdfs:/myinput/graph.txt");//location of file                      in hdfs             filesystem fs = filesystem.get(new configuration());             bufferedreader br=new bufferedreader(new                              inputstreamreader(fs.open(pt)));             string line;             line=br.readline();             while (line != null){                 no_line=no_line+1;                 line=br.readline();             }         }            private string [][]row=new string[no_line][4];          @override                public void map(longwritable key, text value, outputcollector<text,     text> output, reporter reporter) throws ioexception {                      if (i<no_line-1){                  string[] s = value.tostring().split(",");                 (int j=0;j<s.length;j++){                     row[i][j]=(s[j]);                 }                 i=i+1;             }             else{                 string[] s = value.tostring().split(",");                 (int j=0;j<s.length;j++){             //row[i][j]=integer.parseint(s[j]);                 }                 (int i=0;i<no_line-1;i++){                     string a=row[i][0];                     string b=row[i][1]+","+row[i][2]+","+row[i][3];                     output.collect(new text(a),new text(b));                 }             }         }     } 

reducer code -

    import java.io.ioexception;     import java.util.iterator;      import org.apache.hadoop.io.text;     import org.apache.hadoop.mapred.mapreducebase;     import org.apache.hadoop.mapred.outputcollector;     import org.apache.hadoop.mapred.reducer;     import org.apache.hadoop.mapred.reporter;           public class primreducer extends mapreducebase implements          reducer<text, text, text, text> {             public void reduce(text key, iterator<text> values,     outputcollector<text, text> output, reporter reporter) throws ioexception             {         int = 0, b = 0 , c = 0;         output.collect(new text("kishan "), new text("sharma"));         while (values.hasnext()) {             string val[]=(values.next().tostring()).split(",");             a=integer.parseint(val[0]);             b=integer.parseint(val[1]);             c=integer.parseint(val[2]);         }         output.collect(key, new text(a+","+b+","+c));     } } 

in console got logs-

    [training@localhost workspace]$ hadoop jar hierarchical.jar primdriver      myinput/graph.txt cluster5     17/04/07 10:21:18 warn mapred.jobclient: use genericoptionsparser              parsing arguments. applications should implement tool same.     17/04/07 10:21:18 warn snappy.loadsnappy: snappy native library available     17/04/07 10:21:18 info snappy.loadsnappy: snappy native library loaded     17/04/07 10:21:18 info mapred.fileinputformat: total input paths process : 1     17/04/07 10:21:18 info mapred.jobclient: running job: job_201704070816_0007     17/04/07 10:21:19 info mapred.jobclient:  map 0% reduce 0%     17/04/07 10:22:21 info mapred.jobclient:  map 100% reduce 0%     17/04/07 10:22:29 info mapred.jobclient:  map 100% reduce 66%     17/04/07 10:22:53 info mapred.jobclient:  map 100% reduce 100%     17/04/07 10:23:22 info mapred.jobclient: job complete: job_201704070816_0007     17/04/07 10:23:22 info mapred.jobclient: counters: 33     17/04/07 10:23:22 info mapred.jobclient:   file system counters     17/04/07 10:23:22 info mapred.jobclient:     file: number of bytes read=6     17/04/07 10:23:22 info mapred.jobclient:     file: number of bytes written=361924     17/04/07 10:23:22 info mapred.jobclient:     file: number of read operations=0     17/04/07 10:23:22 info mapred.jobclient:     file: number of large read operations=0     17/04/07 10:23:22 info mapred.jobclient:     file: number of write operations=0     17/04/07 10:23:22 info mapred.jobclient:     hdfs: number of bytes read=146     17/04/07 10:23:22 info mapred.jobclient:     hdfs: number of bytes written=0     17/04/07 10:23:22 info mapred.jobclient:     hdfs: number of read operations=3     17/04/07 10:23:22 info mapred.jobclient:     hdfs: number of large read operations=0     17/04/07 10:23:22 info mapred.jobclient:     hdfs: number of write operations=2     17/04/07 10:23:22 info mapred.jobclient:   job counters      17/04/07 10:23:22 info mapred.jobclient:     launched map tasks=1     17/04/07 10:23:22 info mapred.jobclient:     launched reduce tasks=1     17/04/07 10:23:22 info mapred.jobclient:     data-local map tasks=1     17/04/07 10:23:22 info mapred.jobclient:     total time spent maps in occupied slots (ms)=90240     17/04/07 10:23:22 info mapred.jobclient:     total time spent reduces in occupied slots (ms)=31777     17/04/07 10:23:22 info mapred.jobclient:     total time spent maps waiting after reserving slots (ms)=0     17/04/07 10:23:22 info mapred.jobclient:     total time spent reduces waiting after reserving slots (ms)=0     17/04/07 10:23:22 info mapred.jobclient:   map-reduce framework     17/04/07 10:23:22 info mapred.jobclient:     map input records=5     17/04/07 10:23:22 info mapred.jobclient:     map output records=0     17/04/07 10:23:22 info mapred.jobclient:     map output bytes=0     17/04/07 10:23:22 info mapred.jobclient:     input split bytes=104     17/04/07 10:23:22 info mapred.jobclient:     combine input records=0     17/04/07 10:23:22 info mapred.jobclient:     combine output records=0     17/04/07 10:23:22 info mapred.jobclient:     reduce input groups=0     17/04/07 10:23:22 info mapred.jobclient:     reduce shuffle bytes=6     17/04/07 10:23:22 info mapred.jobclient:     reduce input records=0     17/04/07 10:23:22 info mapred.jobclient:     reduce output records=0     17/04/07 10:23:22 info mapred.jobclient:     spilled records=0     17/04/07 10:23:22 info mapred.jobclient:     cpu time spent (ms)=1240     17/04/07 10:23:22 info mapred.jobclient:     physical memory (bytes) snapshot=196472832     17/04/07 10:23:22 info mapred.jobclient:     virtual memory (bytes) snapshot=775897088     17/04/07 10:23:22 info mapred.jobclient:     total committed heap usage (bytes)=177016832     17/04/07 10:23:22 info mapred.jobclient:   org.apache.hadoop.mapreduce.lib.input.fileinputformatcounter     17/04/07 10:23:22 info mapred.jobclient:     bytes_read=42 

when i smaller no_line-1, don't collect anything. condition holds in case, , that's why not seeing map output records.

when start processing first record, no_line initialized @ final value (the actual number of lines in input file "hdfs:/myinput/graph.txt").

at point, i 0. then, when if condition met, i becomes 1 in specific mapper (not @ mappers).* then, i has value 1 (in mapper) , must still less no_line - 1. seems file graph.txt has more 5 lines (i guess).

in summary, setup() executed once before each map() gets executed @ every mapper.

i have no idea want do, , seems difficult understand part. try make clearer , update question more details, if need more help. in else statement, using variable i again seems confusing, not clear if want use local i, or "shadowed" i. doesn't ide give warning that?

*this bad practice, can't know values i take in each mapper, depends on data partitioning.