[HDFS-1143] Implement Background deletion

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 0.22.0
• Component/s: namenode
• Assignee: Scott Chen
• Reporter: Dmytro Molkov
• Created: 11/May/10 18:51
• Updated: 10/Jul/12 21:46
• Resolved: 10/Jul/12 21:46

Description

Right now if you try to delete massive number of files from the namenode it will freeze (sometimes for minutes). Most of the time is spent going through the blocks map and invalidating all the blocks.
This can probably be improved by having a background GC process. The deletion will basically just remove the inode being deleted and then give the subtree that was just deleted to the background thread running cleanup.
This way the namenode becomes available for the clients soon after deletion, and all the heavy operations are done in the background.

Thoughts?

Issue Links

• duplicates: HDFS-1393 When a directory with huge number of files is deleted, the NN becomes unresponsive