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https://issues.apache.org/jira/browse/HADOOP-15999?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran updated HADOOP-15999:
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Status: Patch Available (was: Open)
Patch 007
I never found what the problem with my test setup was -IDE runs would work- but
there's enough going on with trying to retrofit auth/nonauth to existing FS
instances then I concluded it was just caching problem playing up.
Fix:
* explicitly create new guarded/unguarded filesystems in test setup
* with the choice of auth/unauth mode being chosen in the parameter used to
parameterize all the tests.
* (which also allows for the tests to be cut in half, etc, etc)
With this, the tests are working in IDE, single test, parallel tests. That bit,
I'm happy.
now, looking at the code patch, one thing I'm worried about is that the patch
doesn't handle
expiry of tombstones. Ever. Which is still part of the OOB problem.
If a guarded FS deletes a file, and an unguarded client creates it,
getFileStatus on the guarded file will always return FNFE. I think we''ll need
to have an expiry of tombstones, on both auth and nonauth, to stop this.
Thoughts? It'll probably make sense to do that in a followup patch: this one
for these bits of the problem
> S3Guard: 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-15999-007.patch, HADOOP-15999.001.patch,
> HADOOP-15999.002.patch, HADOOP-15999.003.patch, HADOOP-15999.004.patch,
> HADOOP-15999.005.patch, HADOOP-15999.006.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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