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https://issues.apache.org/jira/browse/HADOOP-1093?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12479688
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dhruba borthakur commented on HADOOP-1093:
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I have two questions regarding two snippets of code in method readBuffer() in
ChecksumFilesystem.java.
1. There is a loop of the following form:
boolean endOfFile=false;
while (read < len && !endOfFile) {
int count = datas.read(b, off + read, len - read);
if (count < 0)
endOfFile = true;
else
read += count;
}
Now, is there a possibility that datas.read() returns 0? If so, then the above
might loop indefinitely.
2. Another portion of code:
if (seekToNewSource(oldPos)) {
throw ce;
} else {
retry = true;
}
Isn't it true that seekTonewSource returns true if there is another possible
source for this block. In that case, should not the above check be reversed? if
my observation is correct, the above code might result in an infinite loop.
> 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
> Priority: Blocker
> Fix For: 0.12.1
>
>
> 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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