[
https://issues.apache.org/jira/browse/HADOOP-12107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14608516#comment-14608516
]
Hudson commented on HADOOP-12107:
---------------------------------
SUCCESS: Integrated in Hadoop-Mapreduce-trunk #2190 (See
[https://builds.apache.org/job/Hadoop-Mapreduce-trunk/2190/])
HADOOP-12107. long running apps may have a huge number of StatisticsData
instances under FileSystem (Sangjin Lee via Ming Ma) (mingma: rev
8e1bdc17d9134e01115ae7c929503d8ac0325207)
*
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/FCStatisticsBaseTest.java
*
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java
* hadoop-common-project/hadoop-common/CHANGES.txt
> 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
>
> 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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
