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https://issues.apache.org/jira/browse/HDFS-12748?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16871776#comment-16871776
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Erik Krogen commented on HDFS-12748:
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[~cheersyang] are you still interested in working on this?
The approach of the v3 patch seems good, I just have a few comments:
* I think rather than having a possibility of a null configuration and thus
requiring a null check, it would be simpler to just supply a default conf
object like what is done now.
* Is there actually a possibility of {{ugi}} being null? The
{{System.getProperty()}} here doesn't seem great
* {{new Path}} instead of {{new org.apache.hadoop.fs.Path}} ?
* I don't think we need the {{toUri().toPath()}}; we can just call
{{path.toString()}} directly since {{getHomeDirectory()}} doesn't return a
fully qualified path
> NameNode memory leak when accessing webhdfs GETHOMEDIRECTORY
> ------------------------------------------------------------
>
> Key: HDFS-12748
> URL: https://issues.apache.org/jira/browse/HDFS-12748
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs
> Affects Versions: 2.8.2
> Reporter: Jiandan Yang
> Assignee: Weiwei Yang
> Priority: Major
> Attachments: HDFS-12748.001.patch, HDFS-12748.002.patch,
> HDFS-12748.003.patch
>
>
> In our production environment, the standby NN often do fullgc, through mat we
> found the largest object is FileSystem$Cache, which contains 7,844,890
> DistributedFileSystem.
> By view hierarchy of method FileSystem.get() , I found only
> NamenodeWebHdfsMethods#get call FileSystem.get(). I don't know why creating
> different DistributedFileSystem every time instead of get a FileSystem from
> cache.
> {code:java}
> case GETHOMEDIRECTORY: {
> final String js = JsonUtil.toJsonString("Path",
> FileSystem.get(conf != null ? conf : new Configuration())
> .getHomeDirectory().toUri().getPath());
> return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
> }
> {code}
> When we close FileSystem when GETHOMEDIRECTORY, NN don't do fullgc.
> {code:java}
> case GETHOMEDIRECTORY: {
> FileSystem fs = null;
> try {
> fs = FileSystem.get(conf != null ? conf : new Configuration());
> final String js = JsonUtil.toJsonString("Path",
> fs.getHomeDirectory().toUri().getPath());
> return Response.ok(js).type(MediaType.APPLICATION_JSON).build();
> } finally {
> if (fs != null) {
> fs.close();
> }
> }
> }
> {code}
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