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https://issues.apache.org/jira/browse/HADOOP-2576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12560601#action_12560601 ]
Raghu Angadi commented on HADOOP-2576:
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What is the heartbeat on this cluster? Is it is say large like 1 min? invalidateSet that contains the blocks to delete for each datanode at namenode is actually a array.. each block could be present multiple times in this array.
> Namenode performance degradation over time
> ------------------------------------------
>
> Key: HADOOP-2576
> URL:
https://issues.apache.org/jira/browse/HADOOP-2576> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.16.0
> Reporter: Christian Kunz
> Priority: Blocker
> Fix For: 0.16.0
>
>
> We have a cluster running the same applications again and again with a high turnover of files.
> The performance of these applications seem to be correlated to the lifetime of the namenode:
> After starting the namenode, the applications need increasingly more time to complete, with about 50% more time after 1 week.
> During that time the namenode average cpu usage increases from typically 10% to 30%, memory usage nearly doubles (although the average amount of data on dfs stays the same), and the average load factor increases by a factor of 2-3 (although not significantly high, <2).
> When looking at the namenode and datanode logs, I see a lot of asks to delete blocks coming from the namenode for blocks not in the blockmap of the datanodes, repeatedly for the same blocks.
> When I counted the number of blocks asked by the namenode to be deleted, I noticed a noticeable increase with the lifetime of the namenode (a factor of 2-3 after 1 week).
> This makes me wonder whether the namenode does not purge the list of invalid blocks from non-existing blocks.
> But independently, the namenode has a degradation issue.
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