???????????й?????????????????“org.apache.commons.logging.Log”??????????tasklog????????????Щ?????????????

???????map task?????????????hdfs???????????????????????InputSplit??????hdfs????????????????????????????map???з??n???n=??????map???????????????????????map task??map task????????????????????????????????????????????
public void map(LongWritable key?? List<Pair> value??
OutputCollector<Text?? LongWritable> context?? Reporter reporter)
throws IOException {
????????????
for(int i=0; i < this.threadnum; i++){
SCNThread t = new SCNThread(value?? reporter?? start?? this);
t.start();
this.alivethread.addAndGet(1);
}
????????????????
??????task????????????????????????????????????????????????????
long now = System.currentTimeMillis();
if (now > this.start + this.interval) {
this.start += this.interval;
context.collect(new LongWritable(this.start)?? new LongWritable(
this.writeBlocks));
}
????????????????
???????????key????????value????????????????????????????????????????????Reducer????????????????????????????????????????????????????ж?????Reducer???reduce??????
????public void reduce(Text key?? Iterator<LongWritable> value??
????OutputCollector<Text?? Text> context?? Reporter reporter)
????????????map????????????????key???????????????value??size???????ж????map??????????????????ж????size????????????????map??????????????????????????????????????????size???С?????map????????????????????????????????????????????????????????????????????????????κ?????????????С?????????????
????????????????????hdfs???????????λ???????maptask????????????????λ????????????map task????????????????????
????????????reducer??????????????hdfs???????????????????????????????????????????????????????
?????????????????????????????DDoS???????????????????????????????????????????????????MR??????????????????????????