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https://issues.apache.org/jira/browse/HADOOP-14138?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15979880#comment-15979880
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Steve Loughran commented on HADOOP-14138:
-----------------------------------------
bq. A lot of people consider the core-default files as documentation
they are, but on the basis that you need to create a Configuration(true) for
the basics of talking to anything in a Hadoop cluster, they are effectively a
declarative configuration point.
bq. Hive uses a nice approach where HiveConf.get(ParamName) implicitly picks up
default values. No *-default.xml file here either.
Big issue in Hadoop core is there is no central config point: Configuration,
HdfsConfiguration, YarnConfiguration, JTConf, plus lots of other bits through
the code. For bonus fun, different projects have different world views on
visibility of even fieldnames, with the HDFS project considering even
{{HdfsClientConfigKeys}} to be private data.
w.r.t opening this up, if someone actually makes a commit to allocate time to
do this, and others to review it, then it's worth doing. Otherwise it'll just
be another abandoned wish list item. While I find the current situation
annoying, I have enough half-complete spare-time-work items to get in to worry
about this. Just load Configuration with default=true and not worry about it.
> Remove S3A ref from META-INF service discovery, rely on existing core-default
> entry
> -----------------------------------------------------------------------------------
>
> Key: HADOOP-14138
> URL: https://issues.apache.org/jira/browse/HADOOP-14138
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 2.9.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Critical
> Fix For: 2.8.0, 2.7.4, 3.0.0-alpha3
>
> Attachments: HADOOP-14138.001.patch, HADOOP-14138-branch-2-001.patch
>
>
> As discussed in HADOOP-14132, the shaded AWS library is killing performance
> starting all hadoop operations, due to classloading on FS service discovery.
> This is despite the fact that there is an entry for fs.s3a.impl in
> core-default.xml, *we don't need service discovery here*
> Proposed:
> # cut the entry from
> {{/hadoop-aws/src/main/resources/META-INF/services/org.apache.hadoop.fs.FileSystem}}
> # when HADOOP-14132 is in, move to that, including declaring an XML file
> exclusively for s3a entries
> I want this one in first as its a major performance regression, and one we
> coula actually backport to 2.7.x, just to improve load time slightly there too
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