(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 >
