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https://issues.apache.org/jira/browse/MAPREDUCE-7448?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17764799#comment-17764799
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ASF GitHub Bot commented on MAPREDUCE-7448:
-------------------------------------------
steveloughran commented on code in PR #6038:
URL: https://github.com/apache/hadoop/pull/6038#discussion_r1324843146
##########
hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/output/FileOutputCommitter.java:
##########
@@ -158,6 +158,11 @@ public FileOutputCommitter(Path outputPath,
"output directory:" + skipCleanup + ", ignore cleanup failures: " +
ignoreCleanupFailures);
+ if (algorithmVersion == 1 && skipCleanup) {
+ LOG.warn("Skip cleaning up when using FileOutputCommitter V1 can lead
to unexpected behaviors. " +
+ "For example, committing several times may be allowed
falsely.");
Review Comment:
"Skip cleaning up when using FileOutputCommitter V1 may corrupt the output".
there's another option here: we just ignore the setting on v1 jobs?
it's only there because directory deletion is so O(files) on GCS, and it
targets v2 because that same file-by-file operation means that directory rename
is never atomic; you may as well use the already unsafe v2 algorithm.
> Inconsistent Behavior for FileOutputCommitter V1 to commit successfully many
> times
> ----------------------------------------------------------------------------------
>
> Key: MAPREDUCE-7448
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-7448
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Reporter: ConfX
> Priority: Critical
> Labels: pull-request-available
> Attachments: reproduce.sh
>
>
> h2. What happened
> I turned on {{mapreduce.fileoutputcommitter.cleanup.skipped=true}} and then
> the version 1 of {{FileOutputCommitter}} can commit several times, which is
> unexpected.
> h2. Where's the problem
> In {{{}FileOutputCommitter.commitJobInternal{}}},
> {noformat}
> if (algorithmVersion == 1) {
> for (FileStatus stat: getAllCommittedTaskPaths(context)) {
> mergePaths(fs, stat, finalOutput, context);
> }
> } if (skipCleanup) {
> LOG.info("Skip cleanup the _temporary folders under job's output " +
> "directory in commitJob.");
> ...{noformat}
> Here if we skip cleanup, the _temporary folder would not be deleted and the
> _SUCCESS file would also not be created, which cause the {{mergePaths}} next
> time to not fail.
> h2. How to reproduce
> # set {{{}mapreduce.fileoutputcommitter.cleanup.skipped{}}}={{{}true{}}}
> # run
> {{org.apache.hadoop.mapred.TestFileOutputCommitter#testCommitterWithDuplicatedCommitV1}}
> you should observe
> {noformat}
> java.lang.AssertionError: Duplicate commit successful: wrong behavior for
> version 1.
> at org.junit.Assert.fail(Assert.java:89)
> at
> org.apache.hadoop.mapred.TestFileOutputCommitter.testCommitterWithDuplicatedCommitInternal(TestFileOutputCommitter.java:295)
> at
> org.apache.hadoop.mapred.TestFileOutputCommitter.testCommitterWithDuplicatedCommitV1(TestFileOutputCommitter.java:269){noformat}
> For an easy reproduction, run the reproduce.sh in the attachment.
> We are happy to provide a patch if this issue is confirmed.
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