[ https://issues.apache.org/jira/browse/HADOOP-1182?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12485688 ] 

Christian Kunz commented on HADOOP-1182:
----------------------------------------

Increasing the number of handlers in namenode server seems to help a lot -- no ''Call queue overflow discarding oldest call' warn messages anymore.

CPU still going up to sustained 99.9% for a while at beginning of the job. We will test more.


> DFS Scalability issue with filecache in large clusters
> ------------------------------------------------------
>
>                 Key: HADOOP-1182
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1182
>             Project: Hadoop
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.12.1
>            Reporter: Christian Kunz
>
> When using filecache to distribute supporting files for map/reduce applications in a 1000 node cluster, many map tasks fail  because of timeouts. There was no such problem using a 200 node cluster for the same applications with comparable input data. Either the whole job fails because of too many map failures, or even worse, some map tasks hang indefinitely.
> java.net.SocketTimeoutException: timed out waiting for rpc response
> 	at org.apache.hadoop.ipc.Client.call(Client.java:473)
> 	at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:163)
> 	at org.apache.hadoop.dfs.$Proxy1.exists(Unknown Source)
> 	at org.apache.hadoop.dfs.DFSClient.exists(DFSClient.java:320)
> 	at org.apache.hadoop.dfs.DistributedFileSystem$RawDistributedFileSystem.exists(DistributedFileSystem.java:170)
> 	at org.apache.hadoop.dfs.DistributedFileSystem$RawDistributedFileSystem.open(DistributedFileSystem.java:125)
> 	at org.apache.hadoop.fs.ChecksumFileSystem$FSInputChecker.(ChecksumFileSystem.java:110)
> 	at org.apache.hadoop.fs.ChecksumFileSystem.open(ChecksumFileSystem.java:330)
> 	at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:245)
> 	at org.apache.hadoop.filecache.DistributedCache.createMD5(DistributedCache.java:327)
> 	at org.apache.hadoop.filecache.DistributedCache.ifExistsAndFresh(DistributedCache.java:253)
> 	at org.apache.hadoop.filecache.DistributedCache.localizeCache(DistributedCache.java:169)
> 	at org.apache.hadoop.filecache.DistributedCache.getLocalCache(DistributedCache.java:86)
> 	at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:117)

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.