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Posted to common-issues@hadoop.apache.org by "Daniel Carl Jones (Jira)" <ji...@apache.org> on 2022/10/04 12:32:00 UTC
[jira] [Commented] (HADOOP-16132) Support multipart download in S3AFileSystem
[ https://issues.apache.org/jira/browse/HADOOP-16132?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17612591#comment-17612591 ]
Daniel Carl Jones commented on HADOOP-16132:
--------------------------------------------
Prefetching work (HADOOP-18028) may help resolve this one. The hadoop cat would possibly need to specify it intends to read sequentially or the entire file.
> Support multipart download in S3AFileSystem
> -------------------------------------------
>
> Key: HADOOP-16132
> URL: https://issues.apache.org/jira/browse/HADOOP-16132
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Reporter: Justin Uang
> Priority: Major
> Attachments: HADOOP-16132.001.patch, HADOOP-16132.002.patch, HADOOP-16132.003.patch, HADOOP-16132.004.patch, HADOOP-16132.005.patch, seek-logs-parquet.txt
>
>
> I noticed that I get 150MB/s when I use the AWS CLI
> {code:java}
> aws s3 cp s3://<bucket>/<key> - > /dev/null{code}
> vs 50MB/s when I use the S3AFileSystem
> {code:java}
> hadoop fs -cat s3://<bucket>/<key> > /dev/null{code}
> Looking into the AWS CLI code, it looks like the [download|https://github.com/boto/s3transfer/blob/ca0b708ea8a6a1213c6e21ca5a856e184f824334/s3transfer/download.py] logic is quite clever. It downloads the next couple parts in parallel using range requests, and then buffers them in memory in order to reorder them and expose a single contiguous stream. I translated the logic to Java and modified the S3AFileSystem to do similar things, and am able to achieve 150MB/s download speeds as well. It is mostly done but I have some things to clean up first. The PR is here: https://github.com/palantir/hadoop/pull/47/files
> It would be great to get some other eyes on it to see what we need to do to get it merged.
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