Problem description

The following error occurred during running WordCount program in Eclipse with plug-ins (instead of manually packing and uploading servers):

DEBUG - LocalFetcher 1 going to fetch: attempt_local938878567_0001_m_000000_0
 WARN - job_local938878567_0001
java.lang.Exception: org.apache.hadoop.mapreduce.task.reduce.Shuffle$ShuffleError: error in shuffle in localfetcher#1
    at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
    at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:529)
Caused by: org.apache.hadoop.mapreduce.task.reduce.Shuffle$ShuffleError: error in shuffle in localfetcher#1
    at org.apache.hadoop.mapreduce.task.reduce.Shuffle.run(Shuffle.java:134)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:376)
    at org.apache.hadoop.mapred.LocalJobRunner$Job$ReduceTaskRunnable.run(LocalJobRunner.java:319)
    at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.io.FileNotFoundException: G:/tmp/hadoop-Ferdinand%20Wang/mapred/local/localRunner/Ferdinand%20Wang/jobcache/job_local938878567_0001/attempt_local938878567_0001_m_000000_0/output/file.out.index
    at org.apache.hadoop.fs.RawLocalFileSystem.open(RawLocalFileSystem.java:198)
    at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:766)
    at org.apache.hadoop.io.SecureIOUtils.openFSDataInputStream(SecureIOUtils.java:156)
    at org.apache.hadoop.mapred.SpillRecord.<init>(SpillRecord.java:70)
    at org.apache.hadoop.mapred.SpillRecord.<init>(SpillRecord.java:62)
    at org.apache.hadoop.mapred.SpillRecord.<init>(SpillRecord.java:57)
    at org.apache.hadoop.mapreduce.task.reduce.LocalFetcher.copyMapOutput(LocalFetcher.java:124)
    at org.apache.hadoop.mapreduce.task.reduce.LocalFetcher.doCopy(LocalFetcher.java:102)
    at org.apache.hadoop.mapreduce.task.reduce.LocalFetcher.run(LocalFetcher.java:85)
DEBUG - LocalFetcher 1 going to fetch: attempt_local938878567_0001_m_000000_0
DEBUG - LocalFetcher 1 going to fetch: attempt_local938878567_0001_m_000000_0

Reason

The final problem is the directory in error reporting. This directory is spliced by Hadoop bottom layer with code:

G:/tmp/hadoop-Ferdinand%20Wang/mapred/local/localRunner/Ferdinand%20Wang/jobcache/job_local938878567_0001/attempt_local938878567_0001_m_000000_0/output/file.out.index

Pay attention to% 20, the root cause is that the user name of the computer contains spaces

So we need to change the user name to solve this problem. Of course, we can also create a new user without spaces

Solve the problem

To modify this USERNAME is not so easy, we can test it in one way.

System.getenv("USERNAME")
//Java provides a method to obtain environment variables. If the method is correct, the problem will be solved

I found a lot of blogs and found that many people just changed the user name in the control panel, which is bound to be useless
The solution is as follows