[ http://issues.apache.org/jira/browse/HADOOP-508?page=all ]

Milind Bhandarkar reassigned HADOOP-508:
----------------------------------------

    Assignee: Milind Bhandarkar

> random seeks using FSDataInputStream can become invalid such that reads 
> return invalid data
> -------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-508
>                 URL: http://issues.apache.org/jira/browse/HADOOP-508
>             Project: Hadoop
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.5.0
>            Reporter: Christian Kunz
>         Assigned To: Milind Bhandarkar
>
> Some of my applications using Hadoop DFS  receive wrong data after certain 
> random seeks. After some investigation I believe (without looking at source 
> code of java.io.BufferedInputStream) that it basically boils down to the fact 
> that the method 
> read(byte[] b, int off, int len), when called with an external buffer larger 
> than the internal buffer, reads into the external buffer directly without 
> using the internal buffer anymore, but without invalidating the internal 
> buffer by setting the variable 'count' to 0 such that a subsequent seek to an 
> offset which is closer to the 'position' of the Positioncache than the 
> internal buffersize will put the current position into the internal buffer 
> containing outdated data from somewhere else.

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