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https://issues.apache.org/jira/browse/HDFS-3533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13556016#comment-13556016
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Christoph Rupp commented on HDFS-3533:
--------------------------------------
I am running into the same issue. My current workaround is to retry opening the
file, after a retry it usually works. Sometimes i have to retry multiple times
(up to 4 was the maximum so far.)
{code:title=Pseudocode.java|borderStyle=solid}
void Open(Path path) {
DFSDataInputStream in;
try {
in = (DFSClient.DFSDataInputStream)mFilesystem.open(path);
}
catch (NullPointerException e) {
// wait for a while
Thread.sleep(1000);
// call recursively
Open(path);
return;
}
// ...
}
{code}
My application is very similar to the one described by Amareshwari; i have a
producer and a consumer, both are usually on different datanodes. Every 5
seconds the consumer tries to continue reading the new data.
My question: is this a viable workaround? Do i need the sleep()? Is there a
better/faster way to refresh the node list?
> NPE in DFSClient$DFSInputStream.openInfo
> ----------------------------------------
>
> Key: HDFS-3533
> URL: https://issues.apache.org/jira/browse/HDFS-3533
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client
> Affects Versions: 0.20.203.0
> Reporter: Amareshwari Sriramadasu
> Attachments: cannot-seek-after-eof-dn-logs.txt,
> cannot-seek-after-eof-nn-logs.txt, nn-logs-npe.txt, npe-dn-logs.txt
>
>
> I'm seeing the following NPE:
> java.lang.NullPointerException
> at
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.openInfo(DFSClient.java:1633)
> at
> org.apache.hadoop.hdfs.DFSClient$DFSInputStream.<init>(DFSClient.java:1593)
> at org.apache.hadoop.hdfs.DFSClient.open(DFSClient.java:428)
> at
> org.apache.hadoop.hdfs.DistributedFileSystem.open(DistributedFileSystem.java:187)
> at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:456)
> Here, the file gets opened while it's being written.
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