Arpit Agarwal created HDFS-5412:
-----------------------------------
Summary: Directory scanner fails to propagate volume information
in disk report
Key: HDFS-5412
URL: https://issues.apache.org/jira/browse/HDFS-5412
Project: Hadoop HDFS
Issue Type: Sub-task
Reporter: Arpit Agarwal
Assignee: Arpit Agarwal
The directory scanner periodically compiles a report of differences between the
datanode's on-disk and in-memory state to reconcile differences.
The code to generate the reports is in {{DirectoryScanner#scan}} and
{{DirectoryScanner#getDiskReport}}. It looks like the volume field in
{{ScanInfo}} is not correctly initialized while compiling the diffs. This was
not an issue before but now we depend on the volume information being present.
The bug triggers the following NPE during a scan if a block is present in the
Datanode's in-memory block map but missing on disk:
{code}
java.lang.NullPointerException
at
org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.checkAndUpdate(FsDatasetImpl.java:1404)
at
org.apache.hadoop.hdfs.server.datanode.DirectoryScanner.reconcile(DirectoryScanner.java:416)
at
org.apache.hadoop.hdfs.server.datanode.DirectoryScanner.run(DirectoryScanner.java:365)
at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
at
java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:180)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:204)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:695)
{code}
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