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https://issues.apache.org/jira/browse/HDFS-10383?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15283246#comment-15283246
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Mingliang Liu commented on HDFS-10383:
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Thanks [~xyao] for the review.
I reverted the change of {{createStripedFile()}} because of its intension:
{code:java}
/**
* Creates the metadata of a file in striped layout. This method only
* manipulates the NameNode state without injecting data to DataNode.
* You should disable periodical heartbeat before use this.
* ...
*/
{code}
You made a good point about the double {{completeFile()}}. Yes the
{{DFSStripedStream#close()}} will try to complete the file implicitly when
closing, leading to a double complete file problem. However, there is no data
is injected to DN, plus the client is not aware of the added block by
{{addBlockToFile()}} method which also only manipulates NameNode states.
Suppose we delete the 1st explicit {{completeFile()}} in
{{createStripedFile()}}, the {{DFSStripedOutputStream}} in try-with-resource
will complete a null last block when closing, which will fail for sure.
I think this maybe the reason why {{createStripedFile()}} completes file
explicitly with a valid last block value. The side effect is that, the 2nd
implicit {{completeFile()}} will fail with a {{LeaseExpiredException: File is
not open for writing}}. To handle this, the {{IOUtils#cleanup}} swallows it in
the finally block.
> Safely close resources in DFSTestUtil
> -------------------------------------
>
> Key: HDFS-10383
> URL: https://issues.apache.org/jira/browse/HDFS-10383
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: test
> Reporter: Mingliang Liu
> Assignee: Mingliang Liu
> Attachments: HDFS-10383.000.patch, HDFS-10383.001.patch,
> HDFS-10383.002.patch
>
>
> There are a few of methods in {{DFSTestUtil}} that do not close the resource
> safely, or elegantly. We can use the try-with-resource statement to address
> this problem.
> Specially, as {{DFSTestUtil}} is popularly used in test, we need to preserve
> any exceptions thrown during the processing of the resource while still
> guaranteeing it's closed finally. Take for example,the current implementation
> of {{DFSTestUtil#createFile()}} closes the FSDataOutputStream in the
> {{finally}} block, and when closing if the internal
> {{DFSOutputStream#close()}} throws any exception, which it often does, the
> exception thrown during the processing will be lost. See this [test
> failure|https://builds.apache.org/job/PreCommit-HADOOP-Build/9320/testReport/org.apache.hadoop.hdfs/TestAsyncDFSRename/testAggressiveConcurrentAsyncRenameWithOverwrite/],
> and we have to guess what was the root cause.
> Using try-with-resource, we can close the resources safely, and the
> exceptions thrown both in processing and closing will be available (closing
> exception will be suppressed).
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