Over a million developers have joined DZone.
{{announcement.body}}
{{announcement.title}}

Cassandra / Hadoop: No local connection available?

DZone's Guide to

Cassandra / Hadoop: No local connection available?

· Cloud Zone
Free Resource

Site24x7 - Full stack It Infrastructure Monitoring from the cloud. Sign up for free trial.

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

Site24x7 - Full stack It Infrastructure Monitoring from the cloud. Sign up for free trial.

Topics:

Published at DZone with permission of Brian O' Neill, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

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

{{ parent.tldr }}

{{ parent.urlSource.name }}