[HDFS-5070] Do not initialize the replications queues in the middle of block report processing

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.1.0-beta, 0.23.9
• Component/s: namenode
• Assignee: Unassigned
• Reporter: Kihwal Lee
• Created: 05/Aug/13 21:17
• Updated: 05/Aug/13 21:33

Description

While processing an initial block report in the start-up safe mode, namenode can reach the safe block threshold in the middle of processing the report. This is noticed when checkMode() is called and it causes the replication queues to be initialized.

The safe mode monitor will try to check and leave the safe mode, but can be far behind the write lock, if the initialization takes long (e.g. large number of blocks) and more block reports come in and get queued before it. In this state (replication queue initialized but still in startup safe mode), block report processing can take a long time. In one instance, 4 block report processing took 13 minutes.