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https://issues.apache.org/jira/browse/HDFS-2034?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13045043#comment-13045043
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Todd Lipcon commented on HDFS-2034:
-----------------------------------
In general regarding asserts:
- definitely don't rely on asserts to sanity-check user input - most people run
without asserts on
- I wouldn't be too concerned about performance of asserts unless it's doing
something like an RPC -- since they're only usually on in unit tests, it's
reasonable to trade off for safety over performance
Some notes on the specific patch:
- In this case, I think the assert that Daryn suggested is reasonable -- given
it's a private method, it shouldn't ever have this invalid input, since the
input is already sanity checked in the {{read}} code path, right?
- the {{new ArrayList<LocatedBlock>()}} is unneeded in the usual case, since
the blocks variable is overwritten anyway. Perhaps you could push this to an
{{else}} clause?
> length in getBlockRange becomes -ve when reading only from currently being
> written blk
> --------------------------------------------------------------------------------------
>
> Key: HDFS-2034
> URL: https://issues.apache.org/jira/browse/HDFS-2034
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: John George
> Assignee: John George
> Priority: Minor
> Attachments: HDFS-2034-1.patch, HDFS-2034-1.patch, HDFS-2034-2.patch,
> HDFS-2034.patch
>
>
> This came up during HDFS-1907. Posting an example that Todd posted in
> HDFS-1907 that brought out this issue.
> {quote}
> Here's an example sequence to describe what I mean:
> 1. open file, write one and a half blocks
> 2. call hflush
> 3. another reader asks for the first byte of the second block
> {quote}
> In this case since offset is greater than the completed block length, the
> math in getBlockRange() of DFSInputStreamer.java will set "length" to
> negative.
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