Hi , mapreduce-user seems like a great place for this discussion. general does not.
Thanks! E14 On Jan 19, 2011, at 7:33 PM, venkatesh kavuluri wrote: > (Bcc general@. This is for Hadoop project level discussions. > Includingmapreduce > -user@) > > Liu, > > If you want the count of number of records in your input data set, the > map/reduce framework provides a default counter "Map input records". The > only caution to follow regarding the custom counters is to not exceed 20 per > application as they are very expensive. Generally counters are used to track > few important pieces of information. > > Thanks, > Venkatesh Kavuluri > > 2011/1/19 lei liu <[email protected]> > >> I use counter to statistics file row number in Mapper, example below code: >> >> public void map(LongWritable key, Text value, >> OutputCollector<Text, IntWritable> output, Reporter reporter) >> throws IOException { >> >> try { >> >> reporter.incrCounter("row", "num", 1); >> >> } catch (Throwable e) { >> e.printStackTrace(); >> throw new RuntimeException(e); >> } >> } >> >> Could everyone tell me whether there are any risks do so？ >> >> >> Thanks， >> >> LiuLei >>
