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From "Kihwal Lee (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6293) Issues with OIV processing PB-based fsimages
Date Mon, 28 Apr 2014 15:20:15 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13983095#comment-13983095
] 

Kihwal Lee commented on HDFS-6293:
----------------------------------

Outputting in the new XML format is fast and consumes little memory because it is essentially
dumping what is in the image in order. It does not provide readily usable directory/file information
as it used to in pre-2.4/protobuf versions. 

Using something like the "ls -l" format or any custom visitor for dumping file system tree
will require loading of all inodes upfront and linking them afterwards.  This requires considerably
larger amount of memory. The smallest footprint will be similar to NN's without triplets.
 It is clearly unacceptable.   Reducing memory consumption at the price of considerably longer
processing time is also unacceptable.

> Issues with OIV processing PB-based fsimages
> --------------------------------------------
>
>                 Key: HDFS-6293
>                 URL: https://issues.apache.org/jira/browse/HDFS-6293
>             Project: Hadoop HDFS
>          Issue Type: Bug
>    Affects Versions: 2.4.0
>            Reporter: Kihwal Lee
>            Priority: Blocker
>
> There are issues with OIV when processing fsimages in protobuf. 
> Due to the internal layout changes introduced by the protobuf-based fsimage, OIV consumes
excessive amount of memory.  We have tested with a fsimage with about 140M files/directories.
The peak heap usage when processing this image in pre-protobuf (i.e. pre-2.4.0) format was
about 350MB.  After converting the image to the protobuf format on 2.4.0, OIV would OOM even
with 80GB of heap (max new size was 1GB).  It should be possible to process any image with
the default heap size of 1.5GB.
> Another issue is the complete change of format/content in OIV's XML output.  I also noticed
that the secret manager section has no tokens while there were unexpired tokens in the original
image (pre-2.4.0).  I did not check whether they were also missing in the new pb fsimage.



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