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Posted to common-issues@hadoop.apache.org by "Jason Lowe (JIRA)" <ji...@apache.org> on 2016/01/15 00:54:39 UTC
[jira] [Updated] (HADOOP-12107) long running apps may have a huge
number of StatisticsData instances under FileSystem
[ https://issues.apache.org/jira/browse/HADOOP-12107?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jason Lowe updated HADOOP-12107:
--------------------------------
Fix Version/s: 2.6.4
2.7.3
I committed this to branch-2.7 and branch-2.6.
> long running apps may have a huge number of StatisticsData instances under FileSystem
> -------------------------------------------------------------------------------------
>
> Key: HADOOP-12107
> URL: https://issues.apache.org/jira/browse/HADOOP-12107
> Project: Hadoop Common
> Issue Type: Bug
> Components: fs
> Affects Versions: 2.7.0
> Reporter: Sangjin Lee
> Assignee: Sangjin Lee
> Priority: Critical
> Fix For: 2.8.0, 2.7.3, 2.6.4
>
> Attachments: HADOOP-12107.001.patch, HADOOP-12107.002.patch, HADOOP-12107.003.patch, HADOOP-12107.004.patch, HADOOP-12107.005.patch
>
>
> We observed with some of our apps (non-mapreduce apps that use filesystems) that they end up accumulating a huge memory footprint coming from {{FileSystem$Statistics$StatisticsData}} (in the {{allData}} list of {{Statistics}}).
> Although the thread reference from {{StatisticsData}} is a weak reference, and thus can get cleared once a thread goes away, the actual {{StatisticsData}} instances in the list won't get cleared until any of these following methods is called on {{Statistics}}:
> - {{getBytesRead()}}
> - {{getBytesWritten()}}
> - {{getReadOps()}}
> - {{getLargeReadOps()}}
> - {{getWriteOps()}}
> - {{toString()}}
> It is quite possible to have an application that interacts with a filesystem but does not call any of these methods on the {{Statistics}}. If such an application runs for a long time and has a large amount of thread churn, the memory footprint will grow significantly.
> The current workaround is either to limit the thread churn or to invoke these operations occasionally to pare down the memory. However, this is still a deficiency with {{FileSystem$Statistics}} itself in that the memory is controlled only as a side effect of those operations.
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