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https://issues.apache.org/jira/browse/HADOOP-14138?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15978670#comment-15978670
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Steve Loughran commented on HADOOP-14138:
-----------------------------------------
+use XSD to define schema, allow for type of defval to be declared too.
{code}
<option name="fs.s3a.experimental.input.fadvise" type="String"
field="INPUT_FADVISE" default="INPUT_FADVISE_DEFAULT" deprecated="false"
stability="unstable"
scope="public">
<description>
Which input strategy to use for buffering, seeking and similar when reading
data.
</description>
<value>
normal
</value>
</option>
{code}
(or, if you declare the fieldname, the DEFAULT value falls out). scope (public,
private) would be @ scope attribute; deprecated would set the deprecated tag on
both
{code}
/**
* Which input strategy to use for buffering, seeking and similar when
* reading data.
* Value: {@value}
*/
@InterfaceStability.Unstable
@InterfaceAudience.Public
public static final String INPUT_FADVISE =
"fs.s3a.experimental.input.fadvise";
/** Default value for {@link #INPUT_FADVISE}: value: (@value}. */
@InterfaceAudience.Public
@InterfaceStability.Unstable
public static final String INPUT_FADVISE_DEFAULT = "normal";
{code}
Build wise you'd need a new src/xml area, a build section calling ant for
{{<schemavalidate>}} then {{<xslt>}} to generate things. Oh, and we need
somebody who understands XSL.
> 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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