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https://issues.apache.org/jira/browse/HDFS-11529?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15925183#comment-15925183
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James Clampffer commented on HDFS-11529:
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We added a "hdfsGetLastError" call using thread local state like you're
proposing in the C API for libhdfs++ (HDFS-8707). It's been very useful in
practice for HDFS stuff that doesn't map directly to posix errnos.
> libHDFS still does not return appropriate error information in many cases
> -------------------------------------------------------------------------
>
> Key: HDFS-11529
> URL: https://issues.apache.org/jira/browse/HDFS-11529
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: libhdfs
> Affects Versions: 2.6.0
> Reporter: Sailesh Mukil
> Priority: Critical
> Labels: errorhandling, libhdfs
>
> libHDFS uses a table to compare exceptions against and returns a
> corresponding error code to the application in case of an error.
> However, this table is manually populated and many times is disremembered
> when new exceptions are added.
> This causes libHDFS to return EINTERNAL (or Unknown Error(255)) whenever
> these exceptions are hit. These are some examples of exceptions that have
> been observed on an Error(255):
> org.apache.hadoop.ipc.StandbyException (Operation category WRITE is not
> supported in state standby)
> java.io.EOFException: Cannot seek after EOF
> javax.security.sasl.SaslException: GSS initiate failed [Caused by
> GSSException: No valid credentials provided (Mechanism level: Failed to find
> any Kerberos tgt)
> It is of course not possible to have an error code for each and every type of
> exception, so one suggestion of how this can be addressed is by having a call
> such as hdfsGetLastException() that would return the last exception that a
> libHDFS thread encountered. This way, an application may choose to call
> hdfsGetLastException() if it receives EINTERNAL.
> We can make use of the Thread Local Storage to store this information. Also,
> this makes sure that the current functionality is preserved.
> This is a follow up from HDFS-4997.
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