HADOOP??????????????????
???????????? ???????[ 2012/8/2 10:42:06 ] ????????
?????????????????????????????????????????????hadoop??????У???????hadoop????????????????????????hadoop?????????????????????hadoop????????????顣????????????????????????Щ????????????????????????Щ????????????
??????????????????
????1??reduce???????????????????????????????????????????
?????????????????????л???????????????????????????????????е???ε???????????????
???????????????????hdfs???????и???д???????????reduce???????????????????hdfs???????hdfs?????????????????????????????????Щ????????????
?????????????????????????????????????????????????????????????????????????ж????????????????????????
????2??HADOOP_HOME??????????????
??????????????????????????????????hadoop??????????????????????hadoop dfs –ls path????????????????????????????????????????????????
???????????????????????????????ж??hadoop??????????????????hadoop??????????shell?????????????hadoop?????????????????HADOOP_HOME?μ?hadoop????????HADOOP_HOME??????????????????????????????hadoop?????????????????????????
???????????????????????????hadoop???????????????hadoop?????·?????????rd????????У?hadoop?????·??????????
????3??Hadoop?????????????????
??????????????????????????????????·??????????????????????????????
????????????????????·?????????????????????????rd???????????????????????·???????????????????ж?????????в????????????????????????·??????б??????????????./a/??/a//b??/a/./b????map?????????????·????????map??????????????????????·?????ж??????????????????????????????ж??????????????????κ???????????????????????????????????????????????????????????????hdfs???????????????????????????????
?????????????????????????????????????????棺 Map input records??????????0???????0????????????????????????Map output records????0. Map output records????map????????????0?????????????map??α??????????????????????????????????Reduce input records????0????rduece???????0???????????0???
????4??Hadoop???????????????????
????????????reduce?????????????????????hdfs??????????????????????????????????????????????????????????????????????е?reduce???????????????????????????????????????????????????
???????????????hadoop????map??red?????????????????task???л????????????????????????????Щtask???????task???????task??????????????????task?????????????kill?????task????????????±???task??kill??????????????????????????????????o????????????????????????????????
?????????????????hdfs?????????????????в??????????????в??????????????reduce?н???hdfs??????????????????????????????????????Σ?????????????1?????????????????????????????????????????2?????????????????д???????????磬???????????????????????mapred????
????5??Reduce??????????
????????????????????????淢???е?reduce?????????????е?reduce???????????
??????????????????????hadoop??????????????????????????????????hash???????????·??????????????reduce????????????????
??????????????????hadoop???????????????T????????????????????????????????????????μ????????????????????????????????????????泬?????????kill??????????????????ū??????????key???????????????????????
????6??worker???????????
?????????????task??????????????????????????????????????????
?????????????????????????????????????????????task??????????????????????????worker??????????????????????У????и??????worker?????????????н???????????
??????????????????????????????????????????????????????????????????????????????work????????hy????50?????????????????????????????????????????????????????????棬???????????е?worker????
??????
???·???
??????????????????
2023/3/23 14:23:39???д?ò??????????
2023/3/22 16:17:39????????????????????Щ??
2022/6/14 16:14:27??????????????????????????
2021/10/18 15:37:44???????????????
2021/9/17 15:19:29???·???????·
2021/9/14 15:42:25?????????????
2021/5/28 17:25:47??????APP??????????
2021/5/8 17:01:11