Question

我正在尝试将Hadoop，Pig和Cassandra结合起来，以便能够通过简单的Pig查询处理存储在Cassandra中的数据。问题是我无法让Pig创建实际使用CassandraStorage的Map / Reduce作业。

我所做的是从我的一台集群机器上复制了storage-conf.xml文件，在contrib / pig（Cassandra的源代码发行版）之上，然后将这些内容编译到cassandra_loadfun.jar文件中。

接下来我调整了example-script.pig以包含所有的jar：

register /opt/pig/pig-0.7.0-core.jar;
register /tmp/apache-cassandra-0.6.3-src/lib/libthrift-r917130.jar;
REGISTER /tmp/apache-cassandra-0.6.3-src/contrib/pig/build/cassandra_loadfunc.jar;
rows = LOAD 'cassandra://Keyspace1/Standard1' USING org.apache.cassandra.hadoop.pig.CassandraStorage();
cols = FOREACH rows GENERATE flatten($1);
colnames = FOREACH cols GENERATE $0;
namegroups = GROUP colnames BY $0;
namecounts = FOREACH namegroups GENERATE COUNT($1), group;
orderednames = ORDER namecounts BY $0;
topnames = LIMIT orderednames 50;
dump topnames;

所以，如果我没有弄错的话，那些罐子应该被捆绑到提交给hadoop的工作中。但是在运行这个工作时，它只会向我抛出异常：

2010-08-04 22:11:46,395 [main] ERROR org.apache.pig.tools.grunt.Grunt - ERROR 2117: Unexpected error when launching map reduce job.
2010-08-04 22:11:46,395 [main] ERROR org.apache.pig.tools.grunt.Grunt - org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1066: Unable to open iterator for alias topnames
    at org.apache.pig.PigServer.openIterator(PigServer.java:521)
    at org.apache.pig.tools.grunt.GruntParser.processDump(GruntParser.java:544)
    at org.apache.pig.tools.pigscript.parser.PigScriptParser.parse(PigScriptParser.java:241)
    at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:162)
    at org.apache.pig.tools.grunt.GruntParser.parseStopOnError(GruntParser.java:138)
    at org.apache.pig.tools.grunt.Grunt.exec(Grunt.java:89)
    at org.apache.pig.Main.main(Main.java:391)
Caused by: org.apache.pig.impl.logicalLayer.FrontendException: ERROR 1002: Unable to store alias topnames
    at org.apache.pig.PigServer.store(PigServer.java:577)
    at org.apache.pig.PigServer.openIterator(PigServer.java:504)
    ... 6 more
Caused by: org.apache.pig.backend.executionengine.ExecException: ERROR 2117: Unexpected error when launching map reduce job.
    at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher.launchPig(MapReduceLauncher.java:209)
    at org.apache.pig.backend.hadoop.executionengine.HExecutionEngine.execute(HExecutionEngine.java:308)
    at org.apache.pig.PigServer.executeCompiledLogicalPlan(PigServer.java:835)
    at org.apache.pig.PigServer.store(PigServer.java:569)
    ... 7 more
Caused by: java.lang.RuntimeException: Could not resolve error that occured when launching map reduce job: java.lang.NoClassDefFoundError: org/apache/thrift/TBase
    at org.apache.pig.backend.hadoop.executionengine.mapReduceLayer.MapReduceLauncher$JobControlThreadExceptionHandler.uncaughtException(MapReduceLauncher.java:510)
    at java.lang.Thread.dispatchUncaughtException(Thread.java:1845)

我不明白，因为thrift库是明确列出的，应该捆绑在一起，不是吗？

Answer 1

该例外明确表示无法找到TBase类

java.lang.NoClassDefFoundError：org / apache / thrift / TBase

爆炸捆绑的jar并检查thrift lib jar是否实际存在于正确的位置。旧货罐可能已捆绑在不同的位置。

您也可以尝试将jar放在捆绑jar的lib文件夹中。另一种选择是明确地将jar添加到classpath。

通过Pig提交地图/减少工作时捆绑罐子？

1 个答案: