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From Raghu Angadi <rang...@yahoo-inc.com>
Subject Re: java.io.EOFException: while trying to read 65557 bytes
Date Thu, 07 May 2009 23:12:16 GMT
Albert Sunwoo wrote:
> Thanks for the info!
> I was hoping to get some more specific information though. 

in short : we need to more info.

There are typically 4 machines/processes involved in a write : the 
client and 3 datanodes writing the replicas. To see what really 
happened, you need to provide error message(s) for this block on these 
other parts (at least on 3 datanodes should be useful).

This particular error just implies this datanode is the 2nd of the 3 
datanodes (assuming replication of 3) in the "write pipeline" and its 
connection from the 1st datanode was closed. To deduce more we need more 
info... starting with what happened to that block on the first datanode.

also the 3rd datanode is, the block you should grep for in 
other logs is blk_-7056150840276493498 etc..

You should try to see what could be useful information for others 
diagnose the problem... more than likely you will find the cause 
yourself in the process.


> We are seeing these occur during every run, and as such it's not leaving some folks in
our organization with a good feeling about the reliability of HDFS.
> Do these occur as a result of resources being unavailable?  Perhaps the nodes are too
busy and can no longer service reads from other nodes?  Or if the jobs are causing too much
network traffic?  At first glance the machines do not seemed to be pinned, however I am wondering
if sudden bursts of jobs can be causing these as well.  If so does anyone have configuration
recommendations to minimize or remove these errors under any of these circumstances, or perhaps
there is another explanation?
> Thanks,
> Albert
> On 5/5/09 11:34 AM, "Raghu Angadi" <rangadi@yahoo-inc.com> wrote:
> This can happen for example when a client is killed when it has some
> files open for write. In that case it is an expected error (the log
> should really be at WARN or INFO level).
> Raghu.
> Albert Sunwoo wrote:
>> Hello Everyone,
>> I know there's been some chatter about this before but I am seeing the errors below
on just about every one of our nodes.  Is there a definitive reason on why these are occuring,
is there something that we can do to prevent these?
>> 2009-05-04 21:35:11,764 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: DatanodeRegistration(,
storageID=DS-991582569-, infoPort=50075, ipcPort=50020):DataXceiver
>> java.io.EOFException: while trying to read 65557 bytes
>>         at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.readToBuf(BlockReceiver.java:264)
>>         at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.readNextPacket(BlockReceiver.java:308)
>>         at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receivePacket(BlockReceiver.java:372)
>>         at org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receiveBlock(BlockReceiver.java:524)
>>         at org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:357)
>>         at org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:103)
>>         at java.lang.Thread.run(Thread.java:619)
>> Followed by:
>> 2009-05-04 21:35:20,891 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: PacketResponder
blk_-7056150840276493498_10885 1 Exception java.io.InterruptedIOException: Interruped while
waiting for IO on channel java.nio.channels.Socke
>> tChannel[connected local=/ remote=/]. 59756 millis
timeout left.
>>         at org.apache.hadoop.net.SocketIOWithTimeout$SelectorPool.select(SocketIOWithTimeout.java:277)
>>         at org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:155)
>>         at org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:150)
>>         at org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:123)
>>         at java.io.DataInputStream.readFully(DataInputStream.java:178)
>>         at java.io.DataInputStream.readLong(DataInputStream.java:399)
>>         at org.apache.hadoop.hdfs.server.datanode.BlockReceiver$PacketResponder.run(BlockReceiver.java:853)
>>         at java.lang.Thread.run(Thread.java:619)
>> Thanks,
>> Albert

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