[HADOOP-13496] Include file lengths in Mismatch in length error for distcp

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.9.0, 3.0.0-alpha2, 2.8.2
• Labels: distcp
• Assignee: Ted Yu
• Reporter: Ted Yu
• Created: 12/Aug/16 17:37
• Updated: 08/Jun/17 00:15
• Resolved: 19/Jan/17 11:26

Description

Currently RetriableFileCopyCommand doesn't show the perceived lengths in Mismatch in length error:

2016-08-12 10:23:14,231 ERROR [LocalJobRunner Map Task Executor #0] util.RetriableCommand(89): Failure in Retriable command: Copying hdfs://localhost:53941/user/tyu/test-data/dc7c674a-c463-4798-8260-   c5d1e3440a4b/WALs/10.22.9.171,53952,1471022508087/10.22.9.171%2C53952%2C1471022508087.regiongroup-1.1471022510182 to hdfs://localhost:53941/backupUT/backup_1471022580616/WALs/10.22.9.                   171%2C53952%2C1471022508087.regiongroup-1.1471022510182
java.io.IOException: Mismatch in length of source:hdfs://localhost:53941/user/tyu/test-data/dc7c674a-c463-4798-8260-c5d1e3440a4b/WALs/10.22.9.171,53952,1471022508087/10.22.9.171%2C53952%2C1471022508087.regiongroup-1.1471022510182 and target:hdfs://localhost:53941/backupUT/backup_1471022580616/WALs/.distcp.tmp.attempt_local344329843_0006_m_000000_0
  at org.apache.hadoop.tools.mapred.RetriableFileCopyCommand.compareFileLengths(RetriableFileCopyCommand.java:193)
  at org.apache.hadoop.tools.mapred.RetriableFileCopyCommand.doCopy(RetriableFileCopyCommand.java:126)
  at org.apache.hadoop.tools.mapred.RetriableFileCopyCommand.doExecute(RetriableFileCopyCommand.java:99)
  at org.apache.hadoop.tools.util.RetriableCommand.execute(RetriableCommand.java:87)
  at org.apache.hadoop.tools.mapred.CopyMapper.copyFileWithRetry(CopyMapper.java:281)
  at org.apache.hadoop.tools.mapred.CopyMapper.map(CopyMapper.java:253)
  at org.apache.hadoop.tools.mapred.CopyMapper.map(CopyMapper.java:50)

It would be helpful to include what's the expected length and what's the real length.

Thanks to yzhangal for offline discussion.