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https://issues.apache.org/jira/browse/STORM-837?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14660014#comment-14660014
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ASF GitHub Bot commented on STORM-837:
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Github user revans2 commented on the pull request:
https://github.com/apache/storm/pull/644#issuecomment-128368560
I am fine with those changes in principal. Although I do want to spend
some time reading through the code to convince myself that there are no corner
cases that we are missing.
Also I would love to see some unit tests to show we can recover. I believe
that hsync works on the local file system so you would not need to bring up an
HDFS mini cluster, just create a file system using ```file:///...``` as the URL
and write there.
> HdfsState ignores commits
> -------------------------
>
> Key: STORM-837
> URL: https://issues.apache.org/jira/browse/STORM-837
> Project: Apache Storm
> Issue Type: Bug
> Reporter: Robert Joseph Evans
> Assignee: Arun Mahadevan
> Priority: Critical
>
> HdfsState works with trident which is supposed to provide exactly once
> processing. It does this two ways, first by informing the state about
> commits so it can be sure the data is written out, and second by having a
> commit id, so that double commits can be handled.
> HdfsState ignores the beginCommit and commit calls, and with that ignores the
> ids. This means that if you use HdfsState and your worker crashes you may
> both lose data and get some data twice.
> At a minimum the flush and file rotation should be tied to the commit in some
> way. The commit ID should at a minimum be written out with the data so
> someone reading the data can have a hope of deduping it themselves.
> Also with the rotationActions it is possible for a file that was partially
> written is leaked, and never moved to the final location, because it is not
> rotated. I personally think the actions are too generic for this case and
> need to be deprecated.
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