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https://issues.apache.org/jira/browse/HDFS-1907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13043904#comment-13043904
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Todd Lipcon commented on HDFS-1907:
-----------------------------------
nits:
- positionReadOption is already assigned to false for the first test a few
lines above where you added it
- the new test method shouldn't start with a capital T - our method names are
camelCase, not UpperCamelCase
One question on the logic:
- if the last block is in-progress, but you read from within that block, then
readPastEnd will be false. Hence we will only call getFinalizedBlockRange. But
the last block is not finalized. Does this case work? If so, then that means
getFinalizedBlockRange also includes non-finalized blocks, which is contrary to
its name. Here's an example sequence to describe what I mean:
- open file, write one and a half blocks
- call hflush
- another reader asks for the first byte of the second block
> BlockMissingException upon concurrent read and write: reader was doing file
> position read while writer is doing write without hflush
> ------------------------------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-1907
> URL: https://issues.apache.org/jira/browse/HDFS-1907
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs client
> Affects Versions: 0.23.0
> Environment: Run on a real cluster. Using the latest 0.23 build.
> Reporter: CW Chung
> Assignee: John George
> Attachments: HDFS-1907-2.patch, HDFS-1907-3.patch, HDFS-1907-4.patch,
> HDFS-1907-5.patch, HDFS-1907-5.patch, HDFS-1907.patch
>
>
> BlockMissingException is thrown under this test scenario:
> Two different processes doing concurrent file r/w: one read and the other
> write on the same file
> - writer keep doing file write
> - reader doing position file read from beginning of the file to the visible
> end of file, repeatedly
> The reader is basically doing:
> byteRead = in.read(currentPosition, buffer, 0, byteToReadThisRound);
> where CurrentPostion=0, buffer is a byte array buffer, byteToReadThisRound =
> 1024*10000;
> Usually it does not fail right away. I have to read, close file, re-open the
> same file a few times to create the problem. I'll pose a test program to
> repro this problem after I've cleaned up a bit my current test program.
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