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Jason Lowe commented on HADOOP-12107: ------------------------------------- I recently ran across this on a NodeManager running 2.6 that had been up for a while. Any objections to this being picked back to 2.6 and 2.7? > 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)