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https://issues.apache.org/jira/browse/HADOOP-15392?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16442784#comment-16442784
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Steve Loughran commented on HADOOP-15392:
-----------------------------------------

That Export Snapshot gets filesystems in two places

 * 
[Mapper|https://github.com/apache/hbase/blob/master/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java#L224]:
  created in setup, destroyed in cleanup. Life should be that of the mapper 
alone. 
* CLI entry point 
[doWork|https://github.com/apache/hbase/blob/master/hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/snapshot/ExportSnapshot.java#L915].
 Again, close() at the end, which is more than I often no.

I don't see any leaking of FS instances anywhere: nothing in the HBase code to 
point a finger at. If we are leaking memory in the metrics is because the thing 
uses lots of memory *and* the ref counting isn't working. 

# Is there a config option we can set up to not accrue stuff by default?
# maybe it's the fact that this is running with HBase configs which is making 
it surface. @Krizek: what is your metrics config file here?
# If there's  no way to stop this happening them the metric wire-up has to be 
optional; keep off by default. 

> S3A Metrics in S3AInstrumentation Cause Memory Leaks
> ----------------------------------------------------
>
>                 Key: HADOOP-15392
>                 URL: https://issues.apache.org/jira/browse/HADOOP-15392
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/s3
>    Affects Versions: 3.1.0
>            Reporter: Voyta
>            Priority: Major
>
> While using HBase S3A Export Snapshot utility we started to experience memory 
> leaks of the process after version upgrade.
> By running code analysis we traced the cause to revision 
> 6555af81a26b0b72ec3bee7034e01f5bd84b1564 that added the following static 
> reference (singleton):
> private static MetricsSystem metricsSystem = null;
> When application uses S3AFileSystem instance that is not closed immediately 
> metrics are accumulated in this instance and memory grows without any limit.
>  
> Expectation:
>  * It would be nice to have an option to disable metrics completely as this 
> is not needed for Export Snapshot utility.
>  * Usage of S3AFileSystem should not contain any static object that can grow 
> indefinitely.



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