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https://issues.apache.org/jira/browse/PIG-1231?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12833100#action_12833100
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Alan Gates commented on PIG-1231:
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+1 for patch 2.
> Default DataBagIterator.hasNext() should be idempotent in all cases
> -------------------------------------------------------------------
>
> Key: PIG-1231
> URL: https://issues.apache.org/jira/browse/PIG-1231
> Project: Pig
> Issue Type: Bug
> Components: impl
> Affects Versions: 0.6.0
> Reporter: Daniel Dai
> Assignee: Daniel Dai
> Fix For: 0.6.0
>
> Attachments: PIG-1231-1.patch, PIG-1231-2.patch
>
>
> DefaultDataBagIterator.hasNext() is not repeatable when the below conditions
> met:
> 1. There is no more tuple in the last spill file
> 2. There is no tuples in memory (all contents are spilled to files)
> This is not acceptable cuz the name hasNext() implies that it is idempotent.
> In BagFormat, we do misuse DataBagIterator.hasNext() because of the
> assumption that hasNext() is always idempotent, which leads to some
> mysterious errors.
> Condition 2 seems to be very restrictive, but when the databag is really big,
> the memory can hold less than a couple of tuples, the chance to hit 2. is
> high enough.
> Here is one error we saw:
> Caused by: java.io.IOException: Stream closed
> at
> java.io.BufferedInputStream.getBufIfOpen(BufferedInputStream.java:145)
> at java.io.BufferedInputStream.fill(BufferedInputStream.java:189)
> at java.io.BufferedInputStream.read(BufferedInputStream.java:237)
> at java.io.DataInputStream.readByte(DataInputStream.java:248)
> at org.apache.pig.data.DefaultTuple.readFields(DefaultTuple.java:278)
> at
> org.apache.pig.data.DefaultDataBag$DefaultDataBagIterator.readFromFile(DefaultDataBag.java:237)
> ... 20 more
> This happens because: we call hasNext(), which reach EOF and we close the
> file. Then we call hasNext() again in the assumption that it is idempotent.
> However, the stream is closed so we get this error message.
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