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https://issues.apache.org/jira/browse/HDFS-13924?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16618251#comment-16618251
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Chao Sun commented on HDFS-13924:
---------------------------------
[~vagarychen] yes the stack trace:
{code:java}
Caused by: org.apache.hadoop.hdfs.BlockMissingException: Could not obtain
block: <blockID> file=<filePath>
at
org.apache.hadoop.hdfs.DFSInputStream.chooseDataNode(DFSInputStream.java:1021)
at
org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:641)
at
org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:920)
at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:976)
at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:745)
at java.io.FilterInputStream.read(FilterInputStream.java:83)
at java.io.FilterInputStream.read(FilterInputStream.java:83)
at
com.facebook.presto.hive.parquet.reader.ParquetMetadataReader.readIntLittleEndian(ParquetMetadataReader.java:293)
at
com.facebook.presto.hive.parquet.reader.ParquetMetadataReader.readFooter(ParquetMetadataReader.java:88)
at
com.facebook.presto.hive.parquet.ParquetPageSourceFactory.createParquetPageSource(ParquetPageSourceFactory.java:168)
... 16 more
{code}
Note that we are using HDFS 2.8.2 with some custom patches, so you should look
at the code
[here|https://github.com/apache/hadoop/blob/branch-2.8.2/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L1010].
Even with retry, I think it will still call {{getBlockLocations}} on the same
observer and get the same wrong results.
> Handle BlockMissingException when reading from observer
> -------------------------------------------------------
>
> Key: HDFS-13924
> URL: https://issues.apache.org/jira/browse/HDFS-13924
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Chao Sun
> Priority: Major
>
> Internally we found that reading from ObserverNode may result to
> {{BlockMissingException}}. This may happen when the observer sees a smaller
> number of DNs than active (maybe due to communication issue with those DNs),
> or (we guess) late block reports from some DNs to the observer. This error
> happens in
> [DFSInputStream#chooseDataNode|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java#L846],
> when no valid DN can be found for the {{LocatedBlock}} got from the NN side.
> One potential solution (although a little hacky) is to ask the
> {{DFSInputStream}} to retry active when this happens. The retry logic already
> present in the code - we just have to dynamically set a flag to ask the
> {{ObserverReadProxyProvider}} try active in this case.
> cc [~shv], [~xkrogen], [~vagarychen], [~zero45] for discussion.
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