Namenode not able to accept connections
---------------------------------------

         Key: HADOOP-210
         URL: http://issues.apache.org/jira/browse/HADOOP-210
     Project: Hadoop
        Type: Bug

  Components: dfs  
 Environment: linux
    Reporter: Mahadev konar
 Assigned to: Mahadev konar 


I am running owen's random writer on a 627 node cluster (writing 10GB/node).  
After running for a while (map 12% reduce 1%) I get the following error on the 
Namenode:

Exception in thread "Server listener on port 60000" java.lang.OutOfMemoryError: 
unable to create new native thread
        at java.lang.Thread.start0(Native Method)
        at java.lang.Thread.start(Thread.java:574)
        at org.apache.hadoop.ipc.Server$Listener.run(Server.java:105)

After this, the namenode does not seem to be accepting connections from any of 
the clients. All the DFSClient calls get timeout. Here is a trace for one of 
them:
java.net.SocketTimeoutException: timed out waiting for rpc response
        at org.apache.hadoop.ipc.Client.call(Client.java:305)
        at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:149)
        at org.apache.hadoop.dfs.$Proxy1.open(Unknown Source)
        at 
org.apache.hadoop.dfs.DFSClient$DFSInputStream.openInfo(DFSClient.java:419)
        at org.apache.hadoop.dfs.DFSClient$DFSInputStream.(DFSClient.java:406)
        at org.apache.hadoop.dfs.DFSClient.open(DFSClient.java:171)
        at 
org.apache.hadoop.dfs.DistributedFileSystem.openRaw(DistributedFileSystem.java:78)
        at 
org.apache.hadoop.fs.FSDataInputStream$Checker.(FSDataInputStream.java:46)
        at org.apache.hadoop.fs.FSDataInputStream.(FSDataInputStream.java:228)
        at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:157)
        at 
org.apache.hadoop.mapred.TextInputFormat.getRecordReader(TextInputFormat.java:43)
        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:105)
        at 
org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:785).


The namenode then has around 1% CPU utilization at this time (after the 
outofmemory exception has been thrown). I have profiled the NameNode and it 
seems to be using around a maixmum heap size of 57MB (which is not much). So, 
heap size does not seem to be a problem. It might be happening due to lack of 
Stack space? Any pointers?


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