[HDFS-4996] ClientProtocol#metaSave can be made idempotent by overwriting the output file instead of appending to it - ASF JIRA

Voters

Watch issue

Watchers

Create sub-task

Link

Clone

Update Comment Author

Replace String in Comment

Update Comment Visibility

Delete Comments

XML

Word

Printable

JSON

Details

Type: Improvement
Status: Closed
Priority: Minor
Resolution: Fixed
Affects Version/s: 2.1.0-beta, 3.0.0-alpha1
Fix Version/s: 2.1.0-beta
Component/s: namenode
Labels:
None

Target Version/s:

2.1.0-beta
Hadoop Flags:

Reviewed
Release Note:
The dfsadmin -metasave command has been changed to overwrite the output file. Previously, this command would append to the output file if it already existed.

Description

ClientProtocol#metaSave opens its output file for append. This prevents the operation from being idempotent, because retries can cause unpredictable side effects (single copy of the output vs. multiple copies). As discussed on ~~HDFS-4974~~, the operation could be made idempotent by changing this to open the file for overwrite instead of append.