[
https://issues.apache.org/jira/browse/HDFS-1057?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12876380#action_12876380
]
sam rash commented on HDFS-1057:
--------------------------------
I am addressing the last comments. I have one more question, though, as I have
one test that it still fails and I want to see what you think the expected
behavior should be:
immediate read of a new file:
1. writer creates a file and starts to write and hence blocks are assigned in
the NN
2. a reader gets these locations and contacts DN
3. DN has not yet put the replica in the volumeMap and
FSDataset.getVisibleLength() throws a MissingReplicaException
In 0.20, I made it so that client just treats this as a 0-length file. What
should the behavior in trunk be?
> Concurrent readers hit ChecksumExceptions if following a writer to very end
> of file
> -----------------------------------------------------------------------------------
>
> Key: HDFS-1057
> URL: https://issues.apache.org/jira/browse/HDFS-1057
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: data-node
> Affects Versions: 0.21.0, 0.22.0, 0.20-append
> Reporter: Todd Lipcon
> Assignee: sam rash
> Priority: Blocker
> Attachments: conurrent-reader-patch-1.txt,
> conurrent-reader-patch-2.txt, conurrent-reader-patch-3.txt,
> hdfs-1057-trunk-1.txt, hdfs-1057-trunk-2.txt
>
>
> In BlockReceiver.receivePacket, it calls replicaInfo.setBytesOnDisk before
> calling flush(). Therefore, if there is a concurrent reader, it's possible to
> race here - the reader will see the new length while those bytes are still in
> the buffers of BlockReceiver. Thus the client will potentially see checksum
> errors or EOFs. Additionally, the last checksum chunk of the file is made
> accessible to readers even though it is not stable.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
