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https://issues.apache.org/jira/browse/HADOOP-15999?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16773288#comment-16773288
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Steve Loughran commented on HADOOP-15999:
-----------------------------------------
-1
from {{mvn verify -Dtest=moo -Ds3guard -Ddynamodb -Dscale
-Dit.test=ITestS3GuardOutOfBandOperations }}
{code}
[INFO] -------------------------------------------------------
[INFO] T E S T S
[INFO] -------------------------------------------------------
[INFO] Running org.apache.hadoop.fs.s3a.ITestS3GuardOutOfBandOperations
[ERROR] Tests run: 12, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 29.064
s <<< FAILURE! - in org.apache.hadoop.fs.s3a.ITestS3GuardOutOfBandOperations
[ERROR]
testListingLongerLengthOverwriteAuthoritative(org.apache.hadoop.fs.s3a.ITestS3GuardOutOfBandOperations)
Time elapsed: 1.562 s <<< FAILURE!
java.lang.AssertionError: Values should be different. Actual: 1550689095000
at
org.apache.hadoop.fs.s3a.ITestS3GuardOutOfBandOperations.overwriteFileInListing(ITestS3GuardOutOfBandOperations.java:310)
at
org.apache.hadoop.fs.s3a.ITestS3GuardOutOfBandOperations.testListingLongerLengthOverwriteAuthoritative(ITestS3GuardOutOfBandOperations.java:183)
[INFO]
[INFO] Results:
[INFO]
[ERROR] Failures:
[ERROR]
ITestS3GuardOutOfBandOperations.testListingLongerLengthOverwriteAuthoritative:183->overwriteFileInListing:310->Assert.assertNotEquals:211->Assert.assertNotEquals:199->Assert.failEquals:185->Assert.fail:88
Values should be different. Actual: 1550689095000
[INFO]
{code}
> [s3a] Better support for out-of-band operations
> -----------------------------------------------
>
> Key: HADOOP-15999
> URL: https://issues.apache.org/jira/browse/HADOOP-15999
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.1.0
> Reporter: Sean Mackrory
> Assignee: Gabor Bota
> Priority: Major
> Attachments: HADOOP-15999.001.patch, HADOOP-15999.002.patch,
> HADOOP-15999.003.patch, HADOOP-15999.004.patch, out-of-band-operations.patch
>
>
> S3Guard was initially done on the premise that a new MetadataStore would be
> the source of truth, and that it wouldn't provide guarantees if updates were
> done without using S3Guard.
> I've been seeing increased demand for better support for scenarios where
> operations are done on the data that can't reasonably be done with S3Guard
> involved. For example:
> * A file is deleted using S3Guard, and replaced by some other tool. S3Guard
> can't tell the difference between the new file and delete / list
> inconsistency and continues to treat the file as deleted.
> * An S3Guard-ed file is overwritten by a longer file by some other tool. When
> reading the file, only the length of the original file is read.
> We could possibly have smarter behavior here by querying both S3 and the
> MetadataStore (even in cases where we may currently only query the
> MetadataStore in getFileStatus) and use whichever one has the higher modified
> time.
> This kills the performance boost we currently get in some workloads with the
> short-circuited getFileStatus, but we could keep it with authoritative mode
> which should give a larger performance boost. At least we'd get more
> correctness without authoritative mode and a clear declaration of when we can
> make the assumptions required to short-circuit the process. If we can't
> consider S3Guard the source of truth, we need to defer to S3 more.
> We'd need to be extra sure of any locality / time zone issues if we start
> relying on mod_time more directly, but currently we're tracking the
> modification time as returned by S3 anyway.
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