版本：hive： 0.8.1 hbase：0.92.0 hadoop：1.0.0
错误信息类似如下：
Exception in thread "Thread-169" java.lang.RuntimeException: Error while reading from task log url
at org.apache.hadoop.hive.ql.exec.errors.TaskLogProcessor.getErrors(TaskLogProcessor.java:130)
at org.apache.hadoop.hive.ql.exec.JobDebugger.showJobFailDebugInfo(JobDebugger.java:211)
at org.apache.hadoop.hive.ql.exec.JobDebugger.run(JobDebugger.java:81)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.io.IOException: Server returned HTTP response code: 400 for URL: http://slaver1:50060/tasklog?taskid=attempt_201112211741_0005_m_000000_1&start=-8193
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1436)
at java.net.URL.openStream(URL.java:1010)
at org.apache.hadoop.hive.ql.exec.errors.TaskLogProcessor.getErrors(TaskLogProcessor.java:120)
... 3 more
FAILED: Execution Error, return code 2 from org.apache.hadoop.hive.ql.exec.MapRedTask
解决过程如下：
看错误日志，url是：
http://slaver1:50060/tasklog?taskid=attempt_201112211741_0005_m_000000_1&start=-8193
再看看HADOOP的源码：TaskLogServlet
String attemptIdStr = request.getParameter("attemptid");
if (attemptIdStr == null) {
response.sendError(HttpServletResponse.SC_BAD_REQUEST,
"Argument attemptid is required");
return;
}
所以taskid应该是attemptid ，应该是hadoop的版本不一致导致的。
然后在浏览器里访问：http://slaver1:50060/tasklog?attemptid=attempt_201112211741_0005_m_000000_1&start=-8193
获得真正的错误信息,class not found 导致的，然后就好办了，把对应的jar包扔到hadoop的lib .
stop-mapred.sh
start-mapred.sh
搞定。