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https://issues.apache.org/jira/browse/HADOOP-15209?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran updated HADOOP-15209:
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Status: Patch Available (was: Open)
HADOOP-15209 patch 007
* don't worry about false from deletes. The only FS which *may* return it for
bigger problems is ftp, and ftp doesn't work as a dest for distcp
* just add it to a counter & log. At it means is that a delete of a parent dir
has cut it, but that dir is no longer in the cache.
* print cache size at the end of the run
* tests to verify using counters that there's no files copied over to the
remote store. Tested against: s3a, wasb, adl.
* tried to add counters to the delete operations, but they don't get picked up
in the job results...obviously the committer is special that way.
* and the -i ignore flag also ignores delete() failure, which makes it
consistent.
> DistCp to eliminate needless deletion of files under already-deleted
> directories
> --------------------------------------------------------------------------------
>
> Key: HADOOP-15209
> URL: https://issues.apache.org/jira/browse/HADOOP-15209
> Project: Hadoop Common
> Issue Type: Improvement
> Components: tools/distcp
> Affects Versions: 2.9.0
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Priority: Major
> Attachments: HADOOP-15209-001.patch, HADOOP-15209-002.patch,
> HADOOP-15209-003.patch, HADOOP-15209-004.patch, HADOOP-15209-005.patch,
> HADOOP-15209-006.patch, HADOOP-15209-007.patch
>
>
> DistCP issues a delete(file) request even if is underneath an already deleted
> directory. This generates needless load on filesystems/object stores, and, if
> the store throttles delete, can dramatically slow down the delete operation.
> If the distcp delete operation can build a history of deleted directories,
> then it will know when it does not need to issue those deletes.
> Care is needed here to make sure that whatever structure is created does not
> overload the heap of the process.
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