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我是hadoop的新手，我正在嘗試src/examples中的wordcount/secondsort示例。hadoop：在完成地圖之前在flush map輸出和完成溢出之間發生的減少
單詞計數測試環境：
輸入：
file01.txt
file02.txt
secondsort測試環境：
輸入：
sample01.txt
sample02.txt
這意味着兩個測試都將有2個路徑來處理。 我打印一些日誌信息，試圖瞭解map/reduce的過程。
見之間有什麼開始圖輸出的沖洗和成品溢出0： 的單詞計數程序有另外兩個reduce任務前的最後一個減少而 的secondsort程序只是將減少一次，它的完成。 由於這些程序是如此「小」，我不認爲io.sort.mb/io.sort.refactor會影響這一點。
有人可以解釋一下嗎？
感謝您耐心等待我的Englisth和長日誌。
這些日誌信息（我剪了一些無用的信息，使之短）：
wordcount log:
[[email protected] ~]$ hadoop jar test.jar com.abc.example.test wordcount output
13/08/07 18:14:05 INFO mapred.FileInputFormat: Total input paths to process : 2
13/08/07 18:14:06 INFO mapred.JobClient: Running job: job_local_0001
13/08/07 18:14:06 INFO util.ProcessTree: setsid exited with exit code 0
...
13/08/07 18:14:06 INFO mapred.MapTask: numReduceTasks: 1
13/08/07 18:14:06 INFO mapred.MapTask: io.sort.mb = 100
13/08/07 18:14:06 INFO mapred.MapTask: data buffer = 79691776/99614720
13/08/07 18:14:06 INFO mapred.MapTask: record buffer = 262144/327680
Mapper: 0 | Hello Hadoop GoodBye Hadoop
13/08/07 18:14:06 INFO mapred.MapTask: **Starting flush of map output**
Reduce: GoodBye
Reduce: GoodBye | 1
Reduce: Hadoop
Reduce: Hadoop | 1
Reduce: Hadoop | 1
Reduce: Hello
Reduce: Hello | 1
13/08/07 18:14:06 INFO mapred.Task: Task:attempt_local_0001_m_000000_0 is done. And is in the process of commiting
13/08/07 18:14:06 INFO mapred.LocalJobRunner: hdfs://localhost:8020/user/hadoop/wordcount/file02.txt:0+28
13/08/07 18:14:06 INFO mapred.Task: Task 'attempt_local_0001_m_000000_0' done.
13/08/07 18:14:06 INFO mapred.Task: Using ResourceCalculatorPlugin : [email protected]
13/08/07 18:14:06 INFO mapred.MapTask: numReduceTasks: 1
13/08/07 18:14:06 INFO mapred.MapTask: io.sort.mb = 100
13/08/07 18:14:06 INFO mapred.MapTask: data buffer = 79691776/99614720
13/08/07 18:14:06 INFO mapred.MapTask: record buffer = 262144/327680
13/08/07 18:14:06 INFO mapred.MapTask: **Starting flush of map output**
Reduce: Bye
Reduce: Bye | 1
Reduce: Hello
Reduce: Hello | 1
Reduce: world
Reduce: world | 1
Reduce: world | 1
13/08/07 18:14:06 INFO mapred.MapTask: **Finished spill 0**
13/08/07 18:14:06 INFO mapred.Task: Task:attempt_local_0001_m_000001_0 is done. And is in the process of commiting
13/08/07 18:14:06 INFO mapred.LocalJobRunner: hdfs://localhost:8020/user/hadoop/wordcount/file01.txt:0+22
13/08/07 18:14:06 INFO mapred.Task: Task 'attempt_local_0001_m_000001_0' done.
13/08/07 18:14:06 INFO mapred.Task: Using ResourceCalculatorPlugin : [email protected]
13/08/07 18:14:06 INFO mapred.LocalJobRunner:
13/08/07 18:14:06 INFO mapred.Merger: Merging 2 sorted segments
13/08/07 18:14:06 INFO mapred.Merger: Down to the last merge-pass, with 2 segments left of total size: 77 bytes
13/08/07 18:14:06 INFO mapred.LocalJobRunner:
Reduce: Bye
Reduce: Bye | 1
Reduce: GoodBye
Reduce: GoodBye | 1
Reduce: Hadoop
Reduce: Hadoop | 2
Reduce: Hello
Reduce: Hello | 1
Reduce: Hello | 1
Reduce: world
Reduce: world | 2
13/08/07 18:14:06 INFO mapred.Task: Task:attempt_local_0001_r_000000_0 is done. And is in the process of commiting
...
13/08/07 18:14:07 INFO mapred.JobClient: Reduce input groups=5
13/08/07 18:14:07 INFO mapred.JobClient: Combine output records=6
13/08/07 18:14:07 INFO mapred.JobClient: Physical memory (bytes) snapshot=0
13/08/07 18:14:07 INFO mapred.JobClient: Reduce output records=5
13/08/07 18:14:07 INFO mapred.JobClient: Virtual memory (bytes) snapshot=0
13/08/07 18:14:07 INFO mapred.JobClient: Map output records=8
secondsort log info:
[[email protected] ~]$ hadoop jar example.jar com.abc.example.example secondsort output
13/08/07 17:00:11 INFO input.FileInputFormat: Total input paths to process : 2
13/08/07 17:00:11 WARN snappy.LoadSnappy: Snappy native library not loaded
13/08/07 17:00:12 INFO mapred.JobClient: Running job: job_local_0001
13/08/07 17:00:12 INFO util.ProcessTree: setsid exited with exit code 0
13/08/07 17:00:12 INFO mapred.Task: Using ResourceCalculatorPlugin : [email protected]
13/08/07 17:00:12 INFO mapred.MapTask: io.sort.mb = 100
13/08/07 17:00:12 INFO mapred.MapTask: data buffer = 79691776/99614720
13/08/07 17:00:12 INFO mapred.MapTask: record buffer = 262144/327680
Map: 0 | 5 49
Map: 5 | 9 57
Map: 10 | 19 46
Map: 16 | 3 21
Map: 21 | 9 48
Map: 26 | 7 57
...
13/08/07 17:00:12 INFO mapred.MapTask: **Starting flush of map output**
13/08/07 17:00:12 INFO mapred.MapTask: **Finished spill 0**
13/08/07 17:00:12 INFO mapred.Task: Task:attempt_local_0001_m_000000_0 is done. And is in the process of commiting
13/08/07 17:00:12 INFO mapred.LocalJobRunner:
13/08/07 17:00:12 INFO mapred.Task: Task 'attempt_local_0001_m_000000_0' done.
13/08/07 17:00:12 INFO mapred.Task: Using ResourceCalculatorPlugin : [email protected]
13/08/07 17:00:12 INFO mapred.MapTask: io.sort.mb = 100
13/08/07 17:00:12 INFO mapred.MapTask: data buffer = 79691776/99614720
13/08/07 17:00:12 INFO mapred.MapTask: record buffer = 262144/327680
Map: 0 | 20 21
Map: 6 | 50 51
Map: 12 | 50 52
Map: 18 | 50 53
Map: 24 | 50 54
...
13/08/07 17:00:12 INFO mapred.MapTask: **Starting flush of map output**
13/08/07 17:00:12 INFO mapred.MapTask: **Finished spill 0**
13/08/07 17:00:12 INFO mapred.Task: Task:attempt_local_0001_m_000001_0 is done. And is in the process of commiting
13/08/07 17:00:12 INFO mapred.LocalJobRunner:
13/08/07 17:00:12 INFO mapred.Task: Task 'attempt_local_0001_m_000001_0' done.
13/08/07 17:00:12 INFO mapred.Task: Using ResourceCalculatorPlugin : [email protected]
13/08/07 17:00:12 INFO mapred.LocalJobRunner:
13/08/07 17:00:12 INFO mapred.Merger: Merging 2 sorted segments
13/08/07 17:00:12 INFO mapred.Merger: Down to the last merge-pass, with 2 segments left of total size: 1292 bytes
13/08/07 17:00:12 INFO mapred.LocalJobRunner:
Reduce: 0:35 -----------------
Reduce: 0:35 | 35
Reduce: 0:54 -----------------
...
13/08/07 17:00:12 INFO mapred.Task: Task:attempt_local_0001_r_000000_0 is done. And is in the process of commiting
13/08/07 17:00:12 INFO mapred.LocalJobRunner:
13/08/07 17:00:12 INFO mapred.Task: Task attempt_local_0001_r_000000_0 is allowed to commit now
13/08/07 17:00:12 INFO output.FileOutputCommitter: Saved output of task 'attempt_local_0001_r_000000_0' to output
13/08/07 17:00:12 INFO mapred.LocalJobRunner: reduce > reduce
13/08/07 17:00:12 INFO mapred.Task: Task 'attempt_local_0001_r_000000_0' done.
13/08/07 17:00:13 INFO mapred.JobClient: map 100% reduce 100%
13/08/07 17:00:13 INFO mapred.JobClient: Job complete: job_local_0001
13/08/07 17:00:13 INFO mapred.JobClient: Counters: 22
13/08/07 17:00:13 INFO mapred.JobClient: File Output Format Counters
13/08/07 17:00:13 INFO mapred.JobClient: Bytes Written=4787
...
13/08/07 17:00:13 INFO mapred.JobClient: SPLIT_RAW_BYTES=236
13/08/07 17:00:13 INFO mapred.JobClient: Reduce input records=92
PS：在main（）S下別人退房。
單詞計數：
public static void main(String[] args) throws Exception {
JobConf conf = new JobConf(test.class);
conf.setJobName("wordcount");
conf.setOutputKeyClass(Text.class);
conf.setOutputValueClass(IntWritable.class);
conf.setMapperClass(Map.class);
conf.setCombinerClass(Reduce.class);
conf.setReducerClass(Reduce.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);
}
secondsort：
public static void main(String[] args) throws IOException, InterruptedException, ClassNotFoundException
{
Configuration conf = new Configuration();
Job job = new Job(conf, "secondarysort");
job.setJarByClass(example.class);
job.setMapperClass(Map.class);
job.setReducerClass(Reduce.class);
job.setPartitionerClass(FirstPartitioner.class);
job.setGroupingComparatorClass(GroupingComparator.class);
job.setMapOutputKeyClass(IntPair.class);
job.setMapOutputValueClass(IntWritable.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
如果你不想要任何組合，請從你的主目錄中刪除以下行：'conf.setCombinerClass（Reduce.class）;' – DDW
如果這回答你的問題，請upvote .. – DDW