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https://issues.apache.org/jira/browse/HADOOP-13264?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15328425#comment-15328425
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Seb Mo commented on HADOOP-13264:
---------------------------------
Linked to the related ticket on which a sudden failure causes the JVM to die
with OutOfMemory. In that test I was trying to migrate a couple of million
files while the datanode ran out of diskspace. This caused by client to die,
although I was calling close on the stream, but since that failed, the
mentioned map caused by JVM to die.
Created a simple test that attempts a write while the datanode is down.
> Hadoop HDFS - DFSOutputStream close method fails to clean up resources in
> case no hdfs datanodes are accessible
> ----------------------------------------------------------------------------------------------------------------
>
> Key: HADOOP-13264
> URL: https://issues.apache.org/jira/browse/HADOOP-13264
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 2.7.2
> Reporter: Seb Mo
>
> Using:
> hadoop-hdfs\2.7.2\hadoop-hdfs-2.7.2-sources.jar!\org\apache\hadoop\hdfs\DFSOutputStream.java
> Close method fails when the client can't connect to any data nodes. When
> re-using the same DistributedFileSystem in the same JVM, if all the datanodes
> can't be accessed, then this causes a memory leak as the
> DFSClient#filesBeingWritten map is never cleared after that.
> Here is a test program:
> public static void main(String args[]) throws Exception
> {
> final Configuration conf = new Configuration();
> conf.addResource(new FileInputStream(new
> File("core-site.xml")));
> conf.addResource(new FileInputStream(new
> File("hdfs-site.xml")));
> final DistributedFileSystem newFileSystem =
> (DistributedFileSystem)FileSystem.get(conf);
> OutputStream outputStream = null;
> try
> {
> outputStream = newFileSystem.create(new
> Path("/user/ssmogos", "test1"));
> outputStream.write("test".getBytes());
> }
> catch (IOException e)
> {
> e.printStackTrace();//don't care about this
> }
> finally
> {
> try
> {
> if (outputStream != null)
> outputStream.close();//now this one
> will fail to close the stream
> }
> catch (IOException e)
> {
> e.printStackTrace();//this will list the thrown
> exception from DFSOutputStream->flushInternal->checkClosed
> //TODO the
> DFSOutputStream#close->dfsClient.endFileLease(fileId) is never getting closed
> }
> }
> Field field =
> DFSClient.class.getDeclaredField("filesBeingWritten");
> field.setAccessible(true);
> System.out.print("THIS SHOULD BE EMPTY: " +
> field.get(newFileSystem.getClient()));
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