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From "Sean Mackrory (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HADOOP-13868) Configure multi-part copies and uploads separately
Date Tue, 06 Dec 2016 17:18:58 GMT
Sean Mackrory created HADOOP-13868:
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             Summary: Configure multi-part copies and uploads separately
                 Key: HADOOP-13868
                 URL: https://issues.apache.org/jira/browse/HADOOP-13868
             Project: Hadoop Common
          Issue Type: Bug
            Reporter: Sean Mackrory
            Assignee: Sean Mackrory


I've been looking at a big performance regression when writing to S3 from Spark that appears
to have been introduced with HADOOP-12891.

In the Amazon SDK, the default threshold for multi-part copies is 320x the threshold for multi-part
uploads (and the block size is 20x bigger), so I don't think it's wise for us 

I did some quick tests and it seems to me the sweet spot when multi-part copies start being
faster is around 512MB. It wasn't as significant, but using 104857600 (Amazon's default) for
the blocksize was also slightly better.

I propose we do the following, although they're independent.

(1) Split the configuration. Ideally, I'd like to have fs.s3a.multipart.copy.threshold and
fs.s3a.multipart.upload.threshold (and corresponding properties for the block size). But then
there's the question of what to do with the existing fs.s3a.multipart.* properties. Deprecation?
Leave it as a short-hand for configuring both (that's overridden by the more specific properties?).

(2) Consider increasing the default values. In my tests, 256 MB seemed to be where multipart
uploads came into their own, and 512 MB was where multipart copies started outperforming the
alternative. Would be interested to hear what other people have seen.



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