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https://issues.apache.org/jira/browse/HADOOP-1093?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12483355
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dhruba borthakur commented on HADOOP-1093:
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One proposal to fix this issue:
1. Make the dfsclient *not* invoke reportWrittenBlock(). Instead, the dfsclient
will instruct each datanode in the pipeline to send blockReceived confirmation
to the namenode.
2. The datanode already accumulates all pending blockReceived() calls and does
them through the offerService thread. So, no change is needed to datanode.
3. The getAdditionalBlock() method on the namenode currently checks that all
previously allocated blocks of this file has reached their minimum replication
factor. I plan on removing this check altogether. This is not really required
but is a performance optimization.
4. The close() method on the DFSClient waits for the minimum number of replicas
of each block to be created. This code remains unchanged.
> NNBench generates millions of NotReplicatedYetException in Namenode log
> -----------------------------------------------------------------------
>
> Key: HADOOP-1093
> URL: https://issues.apache.org/jira/browse/HADOOP-1093
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.12.0
> Reporter: Nigel Daley
> Assigned To: dhruba borthakur
> Fix For: 0.13.0
>
>
> Running NNBench on latest trunk (0.12.1 candidate) on a few hundred nodes
> yielded 2.3 million of these exceptions in the NN log:
> 2007-03-08 09:23:03,053 INFO org.apache.hadoop.ipc.Server: IPC Server
> handler 0 on 8020 call error:
> org.apache.hadoop.dfs.NotReplicatedYetException: Not replicated yet
> at
> org.apache.hadoop.dfs.FSNamesystem.getAdditionalBlock(FSNamesystem.java:803)
> at org.apache.hadoop.dfs.NameNode.addBlock(NameNode.java:309)
> at sun.reflect.GeneratedMethodAccessor14.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:597)
> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:336)
> at org.apache.hadoop.ipc.Server$Handler.run(Server.java:559)
> I run NNBench to create files with block size set to 1 and replication set to
> 1. NNBench then writes 1 byte to the file. Minimum replication for the
> cluster is the default, ie 1. If it encounters an exception while trying to
> do either the create or write operations, it loops and tries again. Multiply
> this by 1000 files per node and a few hundred nodes.
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