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https://issues.apache.org/jira/browse/HDFS-3533?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13398187#comment-13398187
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Amareshwari Sriramadasu commented on HDFS-3533:
-----------------------------------------------
Thanks Todd for the inputs. Will look into DN logs and update the issue.
Elaborating more on the usecase : The file is getting flushed every second on
the producer. There is consumer tailing the file every 5 seconds. Below is the
code snippet of the consumer:
{noformat}
{
FSDataInputStream inStream;
BufferedReader reader;
long currentOffset = 0;
while (true) {
if (reader != null) reader.close();
if (inStream != null) inStream.close();
inStream = fs.open(mypath);
reader = new BufferedReader(new InputStreamReader(in));
inStream.seek(currentOffset);
while (true) {
line = reader.readLine();
if (line == null) {
Thread.sleep(5000);
break;
} else {
currentOffset = inStream.getPos();
.....
}
}
}
}
{noformat}
We are hitting NPE in our production cluster atmost once every one hour, where
the file produced is of size 100-150MB per minute. File could be opened
properly after retry.
We are also hitting the following Exception more often than NPE (5 times in one
hour):
{noformat}
java.io.IOException: Cannot seek after EOF
at
org.apache.hadoop.hdfs.DFSClient$DFSInputStream.seek(DFSClient.java:2149)
at
org.apache.hadoop.fs.FSDataInputStream.seek(FSDataInputStream.java:37)
{noformat}
Seeking also works properly after retry.
The second exception looks like another race. If they are not related, I can
raise another issue for the second exception.
> NPE in DFSClient$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
>
> 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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