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https://issues.apache.org/jira/browse/HADOOP-4061?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tsz Wo (Nicholas), SZE updated HADOOP-4061:
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Attachment: 4061_20081120.patch
4061_20081120.patch:
Thanks, Konstantin and Raghu!
@Konstantin
- This is not true. dfs.namenode.decommission.interval is always in seconds,
not minutes. Only the default value is changed. Could you check it again?
- For code refactoring, I am going to do it in the next step. As mentioned
before, I am going to improve decomission performance. For now, I will change
the class name to DecommissionManager and have Monitor as an inner class.
- I would rather rename it to i for iterator and declare it inside the for-loop
header.
Let me create a new issue for improving decomission performance and discuss it
there. I believe we need more thought.
@Raghu> the loop should count 5 decommissioned nodes
Yes, we should count nodes with decommission in progress.
> Large number of decommission freezes the Namenode
> -------------------------------------------------
>
> Key: HADOOP-4061
> URL: https://issues.apache.org/jira/browse/HADOOP-4061
> Project: Hadoop Core
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.17.2
> Reporter: Koji Noguchi
> Assignee: Tsz Wo (Nicholas), SZE
> Attachments: 4061_20081119.patch, 4061_20081120.patch
>
>
> On 1900 nodes cluster, we tried decommissioning 400 nodes with 30k blocks
> each. Other 1500 nodes were almost empty.
> When decommission started, namenode's queue overflowed every 6 minutes.
> Looking at the cpu usage, it showed that every 5 minutes
> org.apache.hadoop.dfs.FSNamesystem$DecommissionedMonitor thread was taking
> 100% of the CPU for 1 minute causing the queue to overflow.
> {noformat}
> public synchronized void decommissionedDatanodeCheck() {
> for (Iterator<DatanodeDescriptor> it = datanodeMap.values().iterator();
> it.hasNext();) {
> DatanodeDescriptor node = it.next();
> checkDecommissionStateInternal(node);
> }
> }
> {noformat}
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