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https://issues.apache.org/jira/browse/HDFS-16896?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17680119#comment-17680119
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ASF GitHub Bot commented on HDFS-16896:
---------------------------------------

mccormickt12 opened a new pull request, #5322:
URL: https://github.com/apache/hadoop/pull/5322

   …etchLocations. ignoredNodes list is only used on hedged read codepath
   
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   ### Description of PR
   clear ignoredNodes list when we clear deadnode list on refetchLocations. 
ignoredNodes list is only used on hedged read codepath
   
   ### How was this patch tested?
   
   
   ### For code changes:
   
   - [ ] Does the title or this PR starts with the corresponding JIRA issue id 
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   - [ ] Object storage: have the integration tests been executed and the 
endpoint declared according to the connector-specific documentation?
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> HDFS Client hedged read has increased failure rate than without hedged read
> ---------------------------------------------------------------------------
>
>                 Key: HDFS-16896
>                 URL: https://issues.apache.org/jira/browse/HDFS-16896
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: hdfs-client
>            Reporter: Tom McCormick
>            Assignee: Tom McCormick
>            Priority: Major
>
> When hedged read is enabled by HDFS client, we see an increased failure rate 
> on reads.
> *stacktrace*
>  
> {code:java}
> Caused by: org.apache.hadoop.hdfs.BlockMissingException: Could not obtain 
> block: BP-1183972111-10.197.192.88-1590025572374:blk_17114848218_16043459722 
> file=/data/tracking/streaming/AdImpressionEvent/daily/2022/07/18/compaction_1/part-r-1914862.1658217125623.1362294472.orc
> at 
> org.apache.hadoop.hdfs.DFSInputStream.refetchLocations(DFSInputStream.java:1077)
> at 
> org.apache.hadoop.hdfs.DFSInputStream.chooseDataNode(DFSInputStream.java:1060)
> at 
> org.apache.hadoop.hdfs.DFSInputStream.chooseDataNode(DFSInputStream.java:1039)
> at 
> org.apache.hadoop.hdfs.DFSInputStream.hedgedFetchBlockByteRange(DFSInputStream.java:1365)
> at org.apache.hadoop.hdfs.DFSInputStream.pread(DFSInputStream.java:1572)
> at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:1535)
> at org.apache.hadoop.fs.FSInputStream.readFully(FSInputStream.java:121)
> at 
> org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:112)
> at 
> org.apache.hadoop.fs.RetryingInputStream.lambda$readFully$3(RetryingInputStream.java:172)
> at org.apache.hadoop.fs.RetryPolicy.lambda$run$0(RetryPolicy.java:137)
> at org.apache.hadoop.fs.NoOpRetryPolicy.run(NoOpRetryPolicy.java:36)
> at org.apache.hadoop.fs.RetryPolicy.run(RetryPolicy.java:136)
> at 
> org.apache.hadoop.fs.RetryingInputStream.readFully(RetryingInputStream.java:168)
> at 
> org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:112)
> at 
> org.apache.hadoop.fs.FSDataInputStream.readFully(FSDataInputStream.java:112)
> at 
> io.trino.plugin.hive.orc.HdfsOrcDataSource.readInternal(HdfsOrcDataSource.java:76)
> ... 46 more
> {code}
>  



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