[
https://issues.apache.org/jira/browse/HDFS-6293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13990204#comment-13990204
]
Haohui Mai commented on HDFS-6293:
----------------------------------
bq. There is existing apps that use a custom Visitor similar to lsr. It outputs
directory entries with full path and list of blocks for files.
[~kihwal], can you please elaborate it? If you're talking about use cases like
hdfs-du, there is no need to construct the whole namespace from bottom up.
Scanning through the records would be sufficient.
bq. That was the first thing I thought about doing, but the processing time
matters too.
It might not be as bad as you thought. I ran an experiments to see how much
time is required to convert an fsimage to a level db on an 8-core Xeon E5530
CPU @ 2.4GHz, 24G memory, 2TB SATA 3 drive @ 7200 rpm. The machine is running
RHEL 6.2, Java 1.6. The numbers reported below are comparable to the numbers
reported in HDFS-5698.
|Size in Old|512M|1G|2G|4G|8G|
|Size in PB|469M|950M|1.9G|3.7G|7.0G|
|Converting to LevelDB (ms)|30505|56531|121579|373108|1047121|
The additional latency for a 8G fsimage is around 15mins, which looks
reasonable for me for the use cases of an offline tool.
> 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, 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.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
