[HADOOP-16878] FileUtil.copy() to throw IOException if the source and destination are the same

• Type: Improvement
• Status: Reopened
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.3.0
• Labels: pull-request-available
• Target Version/s: 3.5.0
• Assignee: Gabor Bota
• Reporter: Gabor Bota
• Created: 24/Feb/20 14:52
• Updated: 16/Jan/24 08:38

Description

We encountered an error during a test in our QE when the file destination and source path were the same. This happened during an ADLS test, and there were no meaningful error messages, so it was hard to find the root cause of the failure.
The error we saw was that file size has changed during the copy operation. The new file creation in the destination - which is the same as the source - creates a file and sets the file length to zero. After this, getting the source file will fail because the sile size changed during the operation.

I propose a solution to at least log in error level in the FileUtil if the source and destination of the copy operation is the same, so debugging issues like this will be easier in the future.

Update: This has been reverted as it caused problems. When rolling back from a branch

• revert MAPREDUCE-7303
• apply HADOOP-17936

Issue Links

• breaks: MAPREDUCE-7303 Fix TestJobResourceUploader failures after HADOOP-16878
• relates to: HADOOP-17936 TestLocalFSCopyFromLocal.testDestinationFileIsToParentDirectory failure after reverting HADOOP-16878
• links to: GitHub Pull Request #1857
• links to: GitHub Pull Request #2383