在安裝好了Hadoop集群后，我們是不是馬上想去實踐一下，做個例子來測試它是否符合我們的要求呢。這樣，我們使用系統的例子來測試，也就最常見的求PI 的值。

          首先要啟動好叢集。hdfs 和yarn相關程序都啟動，並且正常，才能執行mapreduce作業，因為執行作業需要呼叫資源，就必須啟動yarn 服務。

      

    以上是正常的。 我們就可以執行mr 作業了。

2. 在hadoop 目錄下有 share目錄，下面有寫好的例子，打包為jar 檔案，我們可以直接拿來測試。

 命令:  hadoop  jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.3.jar 10 100        

執行結果如下: 日誌輸出:  

Number of Maps  = 10
Samples per Map = 100
19/01/07 09:45:48 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Wrote input for Map #0

Starting Job
19/01/07 09:45:52 INFO Configuration.deprecation: session.id is deprecated. Instead, use dfs.metrics.session-id
19/01/07 09:45:52 INFO jvm.JvmMetrics: Initializing JVM Metrics with processName=JobTracker, sessionId=
19/01/07 09:45:53 INFO input.FileInputFormat: Total input paths to process : 10
19/01/07 09:45:53 INFO mapreduce.JobSubmitter: number of splits:10
19/01/07 09:45:54 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_local127055197_0001
19/01/07 09:45:55 INFO mapreduce.Job: The url to track the job: http://localhost:8080/
19/01/07 09:45:55 INFO mapreduce.Job: Running job: job_local127055197_0001
19/01/07 09:45:55 INFO mapred.LocalJobRunner: OutputCommitter set in config null
19/01/07 09:45:55 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:45:55 INFO mapred.LocalJobRunner: OutputCommitter is org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter
19/01/07 09:45:55 INFO mapred.LocalJobRunner: Waiting for map tasks
19/01/07 09:45:55 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000000_0
19/01/07 09:45:55 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:45:55 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:45:55 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part0:0+118
19/01/07 09:45:56 INFO mapreduce.Job: Job job_local127055197_0001 running in uber mode : false
19/01/07 09:45:57 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:45:57 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:45:57 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:45:57 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:45:57 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:45:57 INFO mapreduce.Job:  map 0% reduce 0%
19/01/07 09:45:57 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:45:58 INFO mapred.LocalJobRunner: 
19/01/07 09:45:58 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:45:58 INFO mapred.MapTask: Spilling map output
19/01/07 09:45:58 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:45:58 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:45:58 INFO mapred.MapTask: Finished spill 0
19/01/07 09:45:58 INFO mapred.Task: Task:attempt_local127055197_0001_m_000000_0 is done. And is in the process of committing
19/01/07 09:45:59 INFO mapred.LocalJobRunner: map
19/01/07 09:45:59 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000000_0' done.
19/01/07 09:45:59 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000000_0
19/01/07 09:45:59 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000001_0
19/01/07 09:45:59 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:45:59 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:45:59 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part1:0+118
19/01/07 09:45:59 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:45:59 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:45:59 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:45:59 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:45:59 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:45:59 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:45:59 INFO mapred.LocalJobRunner: 
19/01/07 09:45:59 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:45:59 INFO mapred.MapTask: Spilling map output
19/01/07 09:45:59 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:45:59 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:45:59 INFO mapred.MapTask: Finished spill 0
19/01/07 09:45:59 INFO mapred.Task: Task:attempt_local127055197_0001_m_000001_0 is done. And is in the process of committing
19/01/07 09:45:59 INFO mapred.LocalJobRunner: map
19/01/07 09:45:59 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000001_0' done.
19/01/07 09:45:59 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000001_0
19/01/07 09:45:59 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000002_0
19/01/07 09:45:59 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:45:59 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:45:59 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part2:0+118
19/01/07 09:45:59 INFO mapreduce.Job:  map 100% reduce 0%
19/01/07 09:45:59 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:45:59 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:45:59 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:45:59 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:45:59 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:45:59 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:45:59 INFO mapred.LocalJobRunner: 
19/01/07 09:45:59 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:45:59 INFO mapred.MapTask: Spilling map output
19/01/07 09:45:59 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:45:59 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:45:59 INFO mapred.MapTask: Finished spill 0
19/01/07 09:45:59 INFO mapred.Task: Task:attempt_local127055197_0001_m_000002_0 is done. And is in the process of committing
19/01/07 09:45:59 INFO mapred.LocalJobRunner: map
19/01/07 09:45:59 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000002_0' done.
19/01/07 09:45:59 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000002_0
19/01/07 09:45:59 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000003_0
19/01/07 09:45:59 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:45:59 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:45:59 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part3:0+118
19/01/07 09:45:59 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:45:59 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:45:59 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:45:59 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:45:59 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:45:59 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:45:59 INFO mapred.LocalJobRunner: 
19/01/07 09:45:59 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:45:59 INFO mapred.MapTask: Spilling map output
19/01/07 09:45:59 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:45:59 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:45:59 INFO mapred.MapTask: Finished spill 0
19/01/07 09:45:59 INFO mapred.Task: Task:attempt_local127055197_0001_m_000003_0 is done. And is in the process of committing
19/01/07 09:45:59 INFO mapred.LocalJobRunner: map
19/01/07 09:45:59 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000003_0' done.
19/01/07 09:45:59 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000003_0
19/01/07 09:45:59 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000004_0
19/01/07 09:45:59 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:45:59 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:45:59 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part4:0+118
19/01/07 09:46:00 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:46:00 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:46:00 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:46:00 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:46:00 INFO mapred.LocalJobRunner: 
19/01/07 09:46:00 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:46:00 INFO mapred.MapTask: Spilling map output
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:46:00 INFO mapred.MapTask: Finished spill 0
19/01/07 09:46:00 INFO mapred.Task: Task:attempt_local127055197_0001_m_000004_0 is done. And is in the process of committing
19/01/07 09:46:00 INFO mapred.LocalJobRunner: map
19/01/07 09:46:00 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000004_0' done.
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000004_0
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000005_0
19/01/07 09:46:00 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:46:00 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:46:00 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part5:0+118
19/01/07 09:46:00 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:46:00 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:46:00 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:46:00 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:46:00 INFO mapred.LocalJobRunner: 
19/01/07 09:46:00 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:46:00 INFO mapred.MapTask: Spilling map output
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:46:00 INFO mapred.MapTask: Finished spill 0
19/01/07 09:46:00 INFO mapred.Task: Task:attempt_local127055197_0001_m_000005_0 is done. And is in the process of committing
19/01/07 09:46:00 INFO mapred.LocalJobRunner: map
19/01/07 09:46:00 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000005_0' done.
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000005_0
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000006_0
19/01/07 09:46:00 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:46:00 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:46:00 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part6:0+118
19/01/07 09:46:00 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:46:00 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:46:00 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:46:00 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:46:00 INFO mapred.LocalJobRunner: 
19/01/07 09:46:00 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:46:00 INFO mapred.MapTask: Spilling map output
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:46:00 INFO mapred.MapTask: Finished spill 0
19/01/07 09:46:00 INFO mapred.Task: Task:attempt_local127055197_0001_m_000006_0 is done. And is in the process of committing
19/01/07 09:46:00 INFO mapred.LocalJobRunner: map
19/01/07 09:46:00 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000006_0' done.
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000006_0
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000007_0
19/01/07 09:46:00 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:46:00 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:46:00 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part7:0+118
19/01/07 09:46:00 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:46:00 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:46:00 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:46:00 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:46:00 INFO mapred.LocalJobRunner: 
19/01/07 09:46:00 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:46:00 INFO mapred.MapTask: Spilling map output
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:46:00 INFO mapred.MapTask: Finished spill 0
19/01/07 09:46:00 INFO mapred.Task: Task:attempt_local127055197_0001_m_000007_0 is done. And is in the process of committing
19/01/07 09:46:00 INFO mapred.LocalJobRunner: map
19/01/07 09:46:00 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000007_0' done.
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000007_0
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000008_0
19/01/07 09:46:00 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:46:00 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:46:00 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part8:0+118
19/01/07 09:46:00 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:46:00 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:46:00 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:46:00 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:46:00 INFO mapred.LocalJobRunner: 
19/01/07 09:46:00 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:46:00 INFO mapred.MapTask: Spilling map output
19/01/07 09:46:00 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:46:00 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:46:00 INFO mapred.MapTask: Finished spill 0
19/01/07 09:46:00 INFO mapred.Task: Task:attempt_local127055197_0001_m_000008_0 is done. And is in the process of committing
19/01/07 09:46:00 INFO mapred.LocalJobRunner: map
19/01/07 09:46:00 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000008_0' done.
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000008_0
19/01/07 09:46:00 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_m_000009_0
19/01/07 09:46:00 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:46:00 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:46:00 INFO mapred.MapTask: Processing split: hdfs://slave4:8020/user/root/QuasiMonteCarlo_1546825548256_803866814/in/part9:0+118
19/01/07 09:46:01 INFO mapred.MapTask: (EQUATOR) 0 kvi 26214396(104857584)
19/01/07 09:46:01 INFO mapred.MapTask: mapreduce.task.io.sort.mb: 100
19/01/07 09:46:01 INFO mapred.MapTask: soft limit at 83886080
19/01/07 09:46:01 INFO mapred.MapTask: bufstart = 0; bufvoid = 104857600
19/01/07 09:46:01 INFO mapred.MapTask: kvstart = 26214396; length = 6553600
19/01/07 09:46:01 INFO mapred.MapTask: Map output collector class = org.apache.hadoop.mapred.MapTask$MapOutputBuffer
19/01/07 09:46:01 INFO mapred.LocalJobRunner: 
19/01/07 09:46:01 INFO mapred.MapTask: Starting flush of map output
19/01/07 09:46:01 INFO mapred.MapTask: Spilling map output
19/01/07 09:46:01 INFO mapred.MapTask: bufstart = 0; bufend = 18; bufvoid = 104857600
19/01/07 09:46:01 INFO mapred.MapTask: kvstart = 26214396(104857584); kvend = 26214392(104857568); length = 5/6553600
19/01/07 09:46:01 INFO mapred.MapTask: Finished spill 0
19/01/07 09:46:01 INFO mapred.Task: Task:attempt_local127055197_0001_m_000009_0 is done. And is in the process of committing
19/01/07 09:46:01 INFO mapred.LocalJobRunner: map
19/01/07 09:46:01 INFO mapred.Task: Task 'attempt_local127055197_0001_m_000009_0' done.
19/01/07 09:46:01 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_m_000009_0
19/01/07 09:46:01 INFO mapred.LocalJobRunner: map task executor complete.
19/01/07 09:46:01 INFO mapred.LocalJobRunner: Waiting for reduce tasks
19/01/07 09:46:01 INFO mapred.LocalJobRunner: Starting task: attempt_local127055197_0001_r_000000_0
19/01/07 09:46:01 INFO output.FileOutputCommitter: File Output Committer Algorithm version is 1
19/01/07 09:46:01 INFO mapred.Task:  Using ResourceCalculatorProcessTree : [ ]
19/01/07 09:46:01 INFO mapred.ReduceTask: Using ShuffleConsumerPlugin:

[email protected]
19/01/07 09:46:01 INFO reduce.MergeManagerImpl: MergerManager: memoryLimit=363285696, maxSingleShuffleLimit=90821424, mergeThreshold=239768576, ioSortFactor=10, memToMemMergeOutputsThreshold=10
19/01/07 09:46:01 INFO reduce.EventFetcher: attempt_local127055197_0001_r_000000_0 Thread started: EventFetcher for fetching Map Completion Events
19/01/07 09:46:01 INFO reduce.LocalFetcher: localfetcher#1 about to shuffle output of map attempt_local127055197_0001_m_000002_0 decomp: 24 len: 28 to MEMORY
19/01/07 09:46:01 INFO reduce.InMemoryMapOutput: Read 24 bytes from map-output for attempt_local127055197_0001_m_000002_0
19/01/07 09:46:01 INFO reduce.MergeManagerImpl: closeInMemoryFile -> map-output of size: 24, inMemoryMapOutputs.size() -> 1, commitMemory -> 0, usedMemory ->24
19/01/07 09:46:01 INFO reduce.LocalFetcher: localfetcher#1 about to shuffle output of map attempt_local127055197_0001_m_000005_0 decomp: 24 len: 28 to MEMORY
19/01/07 09:46:01 INFO reduce.InMemoryMapOutput: Read 24 bytes from map-output for attempt_local127055197_0001_m_000005_0
19/01/07 09:46:01 INFO reduce.MergeManagerImpl: closeInMemoryFile -> map-output of size: 24, inMemoryMapOutputs.size() -> 2.  commitMemory -> 24, usedMemory ->48

。。。。。。

中間不相關的日誌輸出 省略掉了，日誌內容很長。

19/01/07 09:46:02 INFO mapred.LocalJobRunner: reduce > reduce
19/01/07 09:46:02 INFO mapred.Task: Task 'attempt_local127055197_0001_r_000000_0' done.
19/01/07 09:46:02 INFO mapred.LocalJobRunner: Finishing task: attempt_local127055197_0001_r_000000_0
19/01/07 09:46:02 INFO mapred.LocalJobRunner: reduce task executor complete.
19/01/07 09:46:02 INFO mapreduce.Job:  map 100% reduce 100%
19/01/07 09:46:03 INFO mapreduce.Job: Job job_local127055197_0001 completed successfully
19/01/07 09:46:03 INFO mapreduce.Job: Counters: 35
    File System Counters
        FILE: Number of bytes read=3334288
        FILE: Number of bytes written=6451908
        FILE: Number of read operations=0
        FILE: Number of large read operations=0
        FILE: Number of write operations=0
        HDFS: Number of bytes read=7670
        HDFS: Number of bytes written=13195
        HDFS: Number of read operations=242
        HDFS: Number of large read operations=0
        HDFS: Number of write operations=135
    Map-Reduce Framework
        Map input records=10
        Map output records=20
        Map output bytes=180
        Map output materialized bytes=280
        Input split bytes=1420
        Combine input records=0
        Combine output records=0
        Reduce input groups=2
        Reduce shuffle bytes=280
        Reduce input records=20
        Reduce output records=0
        Spilled Records=40
        Shuffled Maps =10
        Failed Shuffles=0
        Merged Map outputs=10
        GC time elapsed (ms)=594
        Total committed heap usage (bytes)=1714962432
    Shuffle Errors
        BAD_ID=0
        CONNECTION=0
        IO_ERROR=0
        WRONG_LENGTH=0
        WRONG_MAP=0
        WRONG_REDUCE=0
    File Input Format Counters 
        Bytes Read=1180
    File Output Format Counters 
        Bytes Written=97
Job Finished in 10.837 seconds
Estimated value of Pi is 3.14800000000000000000

藍色的即 是計算後的最終結果。 

這就是最簡單的mapreduce 作業。 我們也可以在yarn 的8088 埠檢視作業的執行情況。

有結果輸出的，但是web檢視卻有問題，可能是yarn-site.xml 配置檔案有些問題。

在排查一下。結果可以在控制檯檢視到。web檢視的是作業的執行情況，不會顯示執行結果的。