Hi, I just faced an issue this morning on one of my RS.
Here is an extract of the logs 2013-04-09 11:05:33,164 ERROR org.apache.hadoop.hdfs.DFSClient: Exception closing file /hbase/entry_proposed/ae4a5d72d4613728ddbcc5a64262371b/.tmp/ed6a0154ef714cd88faf26061cf248d3 : java.net.SocketException: Too many open files java.net.SocketException: Too many open files at sun.nio.ch.Net.socket0(Native Method) at sun.nio.ch.Net.socket(Net.java:323) at sun.nio.ch.Net.socket(Net.java:316) at sun.nio.ch.SocketChannelImpl.<init>(SocketChannelImpl.java:101) at sun.nio.ch.SelectorProviderImpl.openSocketChannel(SelectorProviderImpl.java:60) at java.nio.channels.SocketChannel.open(SocketChannel.java:142) at org.apache.hadoop.net.StandardSocketFactory.createSocket(StandardSocketFactory.java:58) at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.createBlockOutputStream(DFSClient.java:3423) at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.nextBlockOutputStream(DFSClient.java:3381) at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream.access$2600(DFSClient.java:2589) at org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$DataStreamer.run(DFSClient.java:2829) ulimit is unlimited on all my servers. Is seems there was to many network connections opened. Is there anything HBase can handle in such scenario? It's only hadoop in the stacktrace, so I'm not sure. Can this be related to nproc? I don't think so. I have another tool running on the RS. Using low CPU, low bandwidth but making MANY network HTTP connections... Any suggestion? JM