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https://issues.apache.org/jira/browse/HADOOP-15999?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16783633#comment-16783633
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Gabor Bota commented on HADOOP-15999:
-------------------------------------
It was really me - so running the tests in my ide with the setting:
{noformat}
<property>
<name>fs.s3a.s3guard.test.implementation</name>
<value>local</value>
</property>
{noformat}
Running the same test with *dynamo* everything passes.
Turned out the reason for *NPE*s when using local was we had the issue with the
reference for the localms again. When we rebuild the fs or build a new fs
instance we have to set the same cache and the NPEs are gone.
After fixing the NPEs the next issue is
{{java.util.concurrent.ExecutionException: java.io.FileNotFoundException:}} -
only for *local* again.
In {{expectExceptionWhenReadingOpenFileAPI}} when the following is called:
{code:java}
try (FSDataInputStream in = guardedFs.openFile(testFilePath).build().get()) {
intercept(FileNotFoundException.class, () -> {
byte[] bytes = new byte[text.length()];
return in.read(bytes, 0, bytes.length);
});
}
{code}
The *{{FSDataInputStream in = guardedFs.openFile(testFilePath).build().get()}}*
throws *FNFE*, and that's even before it's expected. That means there's
something wrong going on with open file API is used. I don't have a clue right
now why would this happen just when using local and not when using dynamo, but
I need to figure it out.
> 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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