Over a million developers have joined DZone.

Cassandra / Hadoop: No local connection available?

· Cloud Zone

Download the Essential Cloud Buyer’s Guide to learn important factors to consider before selecting a provider as well as buying criteria to help you make the best decision for your infrastructure needs, brought to you in partnership with Internap.

If you are trying to run the word_count example in Cassandra Hadoop, and you encounter the following exception:

java.lang.RuntimeException: java.lang.UnsupportedOperationException: no local connection available
at org.apache.cassandra.hadoop.ColumnFamilyRecordReader.initialize(ColumnFamilyRecordReader.java:132)
at org.apache.hadoop.mapred.MapTask$NewTrackingRecordReader.initialize(MapTask.java:418)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:620)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:177)
Caused by: java.lang.UnsupportedOperationException: no local connection available
at org.apache.cassandra.hadoop.ColumnFamilyRecordReader.getLocation(ColumnFamilyRecordReader.java:176)
at org.apache.cassandra.hadoop.ColumnFamilyRecordReader.initialize(ColumnFamilyRecordReader.java:113)
... 4 more


Then you have hit a problem with local IP resolution in Java.

Cassandra currently uses the following line to resolve IP addresses;
localAddresses = InetAddress.getAllByName(InetAddress.getLocalHost().getHostAddress());

There are better ways to do this using the NetworkInterface,

But until Cassandra uses that you'll need to make sure that the bit of code above resolves properly by manipulating your /etc/hosts to resolve localhost to match the configuration in Cassandra, which by default is looking for localhost bound to 127.0.0.1.

I submitted a patch for this. If you are having issues, please vote to get the patch accepted.
https://issues.apache.org/jira/browse/CASSANDRA-3211

The Cloud Zone is brought to you in partnership with Internap. Read Bare-Metal Cloud 101 to learn about bare-metal cloud and how it has emerged as a way to complement virtualized services.

Topics:

Published at DZone with permission of Brian O' Neill , DZone MVB .

Opinions expressed by DZone contributors are their own.

{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}