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https://issues.apache.org/jira/browse/AVRO-2280?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16728001#comment-16728001
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Thiruvalluvan M. G. commented on AVRO-2280:
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Thank you [~bwalshe] for identifying the problem and providing an example where
it breaks.
Even through your suggested solution addresses the example problem, it does not
address a more general issue. The trouble is with data file blocks with zero
objects (call them empty blocks) in them. [Avro
specification|https://avro.apache.org/docs/1.8.1/spec.html] allows for empty
blocks. Thus, even if the C++ implementation does not generate empty blocks,
other language bindings may generate them. So the C++ reader should be able to
handle them.
I've made a [pull request|http://https://github.com/apache/avro/pull/414] to
address the reader's problem.
> Calling DataFileWriter::flush() when there is no data to write can
> subsequently cause an exception when the file is read
> ------------------------------------------------------------------------------------------------------------------------
>
> Key: AVRO-2280
> URL: https://issues.apache.org/jira/browse/AVRO-2280
> Project: Apache Avro
> Issue Type: Bug
> Components: c++
> Reporter: Brian Walshe
> Priority: Major
> Labels: newbie, pull-request-available
>
> If you call flush() on a DataFileWriter object that has no data waiting to be
> written, this will produce an empty block at the end of the file which will
> cause an exception on the last call to DataFileReader::read(T& datum)
> h2. Example
> For example adding the following to the Data File unit tests will cause them
> to break
> [https://github.com/bwalshe/avro/blob/7c6a229b2fcbb0b88368e1503a58daef9f43ee64/lang/c%2B%2B/test/DataFileTests.cc#L192]
> h2. Possible Solution
> Altering DataFileWriter::sync() to check if there are objects to be written
> before proceeding will get the code to pass the unit tests. e.g.:
> [https://github.com/bwalshe/avro/blob/7c6a229b2fcbb0b88368e1503a58daef9f43ee64/lang/c%2B%2B/impl/DataFile.cc#L141
>
> |https://github.com/bwalshe/avro/blob/7c6a229b2fcbb0b88368e1503a58daef9f43ee64/lang/c%2B%2B/impl/DataFile.cc#L141]
>
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