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From "Aaron Fabbri (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-14020) Optimize dirListingUnion
Date Mon, 20 Feb 2017 05:12:44 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-14020?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15874037#comment-15874037
] 

Aaron Fabbri commented on HADOOP-14020:
---------------------------------------

Shoot, I just noticed a bug this patch introduced.. The offending portion is here:

{noformat}
-      if (dirMeta.get(s.getPath()) == null) {
-        dirMeta.put(s);
-      }
+      changed = changed || dirMeta.put(s);
+    }
+
{noformat}

hint: Logical OR is a short-circuit operator.

Sorry I didn't catch this in original review.. I'll file a JIRA now.  Easy fix, but should
probably come with a unit test for dirListingUnion().

> Optimize dirListingUnion
> ------------------------
>
>                 Key: HADOOP-14020
>                 URL: https://issues.apache.org/jira/browse/HADOOP-14020
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/s3
>            Reporter: Sean Mackrory
>            Assignee: Sean Mackrory
>             Fix For: HADOOP-13345
>
>         Attachments: HADOOP-14020-HADOOP-13345.001.patch, HADOOP-14020-HADOOP-13345.002.patch,
HADOOP-14020-HADOOP-13345.003.patch, HADOOP-14020-HADOOP-13345.004.patch
>
>
> There's a TODO in dirListingUnion:
> {quote}// TODO optimize for when allowAuthoritative = false{quote}
> There will be cases when we can intelligently avoid a round trip: if S3A results are
a subset or the metadatastore results (including them being equal or empty) then writing back
will do nothing (although perhaps that should set the authoritative flag if it isn't set already).
> There may also be cases where users want to just skip that altogether. It's wasted work
if authoritative mode is disabled, so perhaps we want to trigger a skip if that's false, or
perhaps it should be a separate property. First one makes for simpler config, second is more
flexible...



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