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https://issues.apache.org/jira/browse/HDFS-6293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13996442#comment-13996442
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Kihwal Lee commented on HDFS-6293:
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Here is recap.
* oiv_legacy for debugging and inspecting old fsimages. As long as NN is
capable of reading and upgrading from it, we should keep it.
* NN's ability to save in old fsimage format: This should go away once we have
a more sustainable solution. Postprocessing ([~wheat9] 's proposal) will cover
many use cases. We may need something else. This is to be determined.
* Keep adding features to the old fsimage format: Please don't!
* Changing the layout of the new PB-based fsimage back to the old way: Heck no!
We will deprecate NN's ability to save in the old fsimage format, once we agree
on what the long term solution is. We should create a separate JIRA and
continue discussion.
As [~sureshms] suggested, I will prepare the patch for trunk as well with
[~ajisakaa]'s comment incorporated.
> 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
> Assignee: Haohui Mai
> Priority: Blocker
> Attachments: HDFS-6293.000.patch, HDFS-6293.001.patch,
> HDFS-6293.002-save-deprecated-fsimage.patch,
> HDFS-6293_sbn_ckpt_retention.patch,
> HDFS-6293_sbn_ckpt_retention_oiv_legacy.patch, Heap Histogram.html
>
>
> 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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