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https://issues.apache.org/jira/browse/MAPREDUCE-6854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17079658#comment-17079658
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Hadoop QA commented on MAPREDUCE-6854:
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| (x) *{color:red}-1 overall{color}* |
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|| Vote || Subsystem || Runtime || Comment ||
| {color:blue}0{color} | {color:blue} reexec {color} | {color:blue} 0m
0s{color} | {color:blue} Docker mode activated. {color} |
| {color:red}-1{color} | {color:red} patch {color} | {color:red} 0m 7s{color}
| {color:red} MAPREDUCE-6854 does not apply to trunk. Rebase required? Wrong
Branch? See https://wiki.apache.org/hadoop/HowToContribute for help. {color} |
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|| Subsystem || Report/Notes ||
| JIRA Issue | MAPREDUCE-6854 |
| JIRA Patch URL |
https://issues.apache.org/jira/secure/attachment/12856176/HADOOP-6854-002.patch
|
| Console output |
https://builds.apache.org/job/PreCommit-MAPREDUCE-Build/7752/console |
| Powered by | Apache Yetus 0.8.0 http://yetus.apache.org |
This message was automatically generated.
> Each map task should create a unique temporary name that includes an object
> name
> --------------------------------------------------------------------------------
>
> Key: MAPREDUCE-6854
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6854
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: distcp
> Affects Versions: 3.0.0-alpha2
> Reporter: Gil Vernik
> Priority: Major
> Labels: patch
> Attachments: HADOOP-6854-001.patch, HADOOP-6854-002.patch
>
>
> Consider an example: a local file "/data/a.txt" need to be copied into
> swift://container.service/data/a.txt
> The way distcp works is that first it will upload "/data/a.txt" into
> swift://container.mil01/data/.distcp.tmp.attempt_local2036034928_0001_m_000000_0
> Upon completion distcp will move
> swift://container.mil01/data/.distcp.tmp.attempt_local2036034928_0001_m_000000_0
> into swift://container.mil01/data/a.txt
> ************************************
> The temporary file naming convention assumes that each map task will
> sequentially create objects as swift://container.mil01/.distcp.tmp.attempt_ID
> and then rename them to the final names. Most of Hadoop eco system
> components use object.name which is part of the temporary name, however
> distcp doesn't use such approach.
> This JIRA propose to add a configuration key indicating that temporary
> objects will also include object name as part of their temporary file name,
> For example
> "/data/a.txt" will be uploaded into
> "swift://container.mil01/data/a.txt.distcp.tmp.attempt_local2036034928_0001_m_000000_0"
> "a.txt.distcp.tmp.attempt_local2036034928_0001_m_000000_0" doesn't affects
> flows in the access drivers, since "a.txt" is not considered as a
> sub-directory so no special operations will be taken.
> The benefits of the patch :
> 1. Temp object names will be better distributed in object stores, since they
> all has different prefix.
> 2. Sometimes it's not possible to debug what data is copied and what failed.
> Sometimes temp files are not renamed, it will be much better if expecting
> temp name - one can figure what object names were copied.
> 3. Different systems may expect
> "a.txt.distcp.tmp.attempt_local2036034928_0001_m_000000_0" and extract value
> prior "distcp.tmp" thus getting destination object name.
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