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https://issues.apache.org/jira/browse/HADOOP-16852?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sneha Vijayarajan updated HADOOP-16852:
---------------------------------------
    Resolution: Fixed
        Status: Resolved  (was: Patch Available)

> ABFS: Send error back to client for Read Ahead request failure
> --------------------------------------------------------------
>
>                 Key: HADOOP-16852
>                 URL: https://issues.apache.org/jira/browse/HADOOP-16852
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/azure
>    Affects Versions: 3.3.1
>            Reporter: Sneha Vijayarajan
>            Assignee: Sneha Vijayarajan
>            Priority: Major
>
> Issue seen by a customer:
> The failed requests we were seeing in the AbfsClient logging actually never 
> made it out over the wire. We have found that there’s an issue with ADLS 
> passthrough and the 8 read ahead threads that ADLSv2 spawns in 
> ReadBufferManager.java. We depend on thread local storage in order to get the 
> right JWT token and those threads do not have the right information in their 
> thread local storage. Thus, when they pick up a task from the read ahead 
> queue they fail by throwing an AzureCredentialNotFoundException exception in 
> AbfsRestOperation.executeHttpOperation() where it calls 
> client.getAccessToken(). This exception is silently swallowed by the read 
> ahead threads in ReadBufferWorker.run(). As a result, every read ahead 
> attempt results in a failed executeHttpOperation(), but still calls 
> AbfsClientThrottlingIntercept.updateMetrics() and contributes to throttling 
> (despite not making it out over the wire). After the read aheads fail, the 
> main task thread performs the read with the right thread local storage 
> information and succeeds, but first sleeps for up to 10 seconds due to the 
> throttling.



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