[HADOOP-1501] Block reports from all datanodes arrive at the namenode within a small band of time

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.14.0
• Assignee: Dhruba Borthakur
• Reporter: Dhruba Borthakur
• Created: 19/Jun/07 06:56
• Updated: 08/Jul/09 16:42
• Resolved: 20/Jun/07 21:58

Description

I have a 2000 node cluster and the block report interval is set to 1 hour. Most block report arrive within a few minutes of one another. For example, I have seen block reports from all 2000 nodes arrive within 5 minutes of one another. This causes CPU overload on the namenode, causing dropped calls in Call queue.

My proposal is to make the datanode send a block report as soon as the datanode starts. Then, it waits for a random time between 0 to 1 hour (the configured value) before sending the nect block report. From then on, block reports from that datanode are sent once every 1 hour (the configured value).