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https://issues.apache.org/jira/browse/HDFS-7996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14387466#comment-14387466
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Colin Patrick McCabe edited comment on HDFS-7996 at 4/3/15 9:13 PM:
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The {{BlockReceiver}} should either be closed, or not closed. Having lots of
subtly different close functions just makes it hard to think about.
It would be much better to add a function like
{{BlockReceiver#claimReplicaHandler}} and have that function return
{{BlockReceiver#replicaHandler}} (and set {{BlockReceiver#replicaHandler}} to
null). Then {{finalizeBlock}} can hold on to the {{replicaHandler}} and its
associated volume for as long as it wants.
I also notice an existing bug in {{BlockReceiver#close}}... if there is an
{{IOException}} closing the data or metadata streams, the volume reference will
never be removed. We should fix this with a finally block. Similarly, if
there is an IOE closing one stream, we should try to close the other stream
rather than giving up. Otherwise we have a file descriptor leak on IO error.
[Edit: actually, the streams will be closed on an IOE, but not on a
RuntimeException/]
was (Author: cmccabe):
The {{BlockReceiver}} should either be closed, or not closed. Having lots of
subtly different close functions just makes it hard to think about.
It would be much better to add a function like
{{BlockReceiver#claimReplicaHandler}} and have that function return
{{BlockReceiver#replicaHandler}} (and set {{BlockReceiver#replicaHandler}} to
null). Then {{finalizeBlock}} can hold on to the {{replicaHandler}} and its
associated volume for as long as it wants.
I also notice an existing bug in {{BlockReceiver#close}}... if there is an
{{IOException}} closing the data or metadata streams, the volume reference will
never be removed. We should fix this with a finally block. Similarly, if
there is an IOE closing one stream, we should try to close the other stream
rather than giving up. Otherwise we have a file descriptor leak on IO error.
> After swapping a volume, BlockReceiver reports ReplicaNotFoundException
> -----------------------------------------------------------------------
>
> Key: HDFS-7996
> URL: https://issues.apache.org/jira/browse/HDFS-7996
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode
> Affects Versions: 2.6.0
> Reporter: Lei (Eddy) Xu
> Assignee: Lei (Eddy) Xu
> Priority: Critical
> Attachments: HDFS-7996.000.patch, HDFS-7996.001.patch,
> HDFS-7996.002.patch
>
>
> When removing a disk from an actively writing DataNode, the BlockReceiver
> working on the disk throws {{ReplicaNotFoundException}} because the replicas
> are removed from the memory:
> {code}
> 2015-03-26 08:02:43,154 INFO
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl: Removed
> volume: /data/2/dfs/dn/current
> 2015-03-26 08:02:43,163 INFO org.apache.hadoop.hdfs.server.common.Storage:
> Removing block level storage:
> /data/2/dfs/dn/current/BP-51301509-10.20.202.114-1427296597742
> 2015-03-26 08:02:43,163 WARN org.apache.hadoop.hdfs.server.datanode.DataNode:
> IOException in BlockReceiver.run():
> org.apache.hadoop.hdfs.server.datanode.ReplicaNotFoundException: Cannot
> append to a non-existent replica
> BP-51301509-10.20.202.114-1427296597742:blk_1073742979_2160
> at
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.getReplicaInfo(FsDatasetImpl.java:615)
> at
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.finalizeBlock(FsDatasetImpl.java:1362)
> at
> org.apache.hadoop.hdfs.server.datanode.BlockReceiver$PacketResponder.finalizeBlock(BlockReceiver.java:1281)
> at
> org.apache.hadoop.hdfs.server.datanode.BlockReceiver$PacketResponder.run(BlockReceiver.java:1241)
> at java.lang.Thread.run(Thread.java:745)
> {code}
> {{FsVolumeList#removeVolume}} waits all threads release {{FsVolumeReference}}
> on the volume to be removed, however, in {{PacketResponder#finalizeBlock()}},
> it calls
> {code}
> private void finalizeBlock(long startTime) throws IOException {
> BlockReceiver.this.close();
> final long endTime = ClientTraceLog.isInfoEnabled() ? System.nanoTime()
> : 0;
> block.setNumBytes(replicaInfo.getNumBytes());
> datanode.data.finalizeBlock(block);
> {code}
> The {{FsVolumeReference}} was released in {{BlockReceiver.this.close()}}
> before calling {{datanode.data.finalizeBlock(block)}}.
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