The processor is expected to call start() before using the input. That’s the recommended approach.
The start() call that you see if an optimization that we do by calling start() implicitly once at the beginning of container execution. This hides some of the initial class loading latency for some inputs. This may disappear once those inputs can startup faster. You must call start() in your processor. Bikas *From:* Thaddeus Diamond [mailto:[email protected]] *Sent:* Thursday, August 07, 2014 1:10 PM *To:* [email protected] *Subject:* ShuffledMergedInput not started Is there a race condition with input.start()? I was under the impression I didn't need to use it since it's in the initialize() method of the LogicalIOProcessorRuntimeTask, but I saw this in one of the logs of a task attempt. 2014-08-07 18:55:23,487 INFO [AsyncDispatcher event handler] org.apache.tez.dag.history.HistoryEventHandler: [HISTORY][DAG:dag_1407259853327_0029_2][Event:TASK_ATTEMPT_FINISHED]: vertexName=8b013089-9aa9-4da3-9ab9-cca97fdf6b7c, taskAttemptId=attempt_1407259853327_0029_2_01_000000_0, startTime=1407437720449, finishTime=1407437723472, timeTaken=3023, status=FAILED, diagnostics=Error: Failure while running task:java.lang.IllegalStateException: Due to KeyValuesReader behavior you must alternate calls to hasNext()/next() at com.google.common.base.Preconditions.checkState(Preconditions.java:145) at com.hadapt.exec.tez.VectorizedRowBatchFromKeyValueIterator.hasNext(VectorizedRowBatchFromKeyValueIterator.java:45) at com.hadapt.exec.tez.VectorizedRowBatchFromKeyValueIterator.next(VectorizedRowBatchFromKeyValueIterator.java:66) at com.hadapt.exec.tez.VectorizedRowBatchFromKeyValueIterator.next(VectorizedRowBatchFromKeyValueIterator.java:24) at com.hadapt.exec.tez.VectorOperatorProcessor.run(VectorOperatorProcessor.java:116) at org.apache.tez.runtime.LogicalIOProcessorRuntimeTask.run(LogicalIOProcessorRuntimeTask.java:324) at org.apache.tez.runtime.task.TezTaskRunner$TaskRunnerCallable$1.run(TezTaskRunner.java:180) at org.apache.tez.runtime.task.TezTaskRunner$TaskRunnerCallable$1.run(TezTaskRunner.java:172) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:415) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1554) at org.apache.tez.runtime.task.TezTaskRunner$TaskRunnerCallable.call(TezTaskRunner.java:172) at org.apache.tez.runtime.task.TezTaskRunner$TaskRunnerCallable.call(TezTaskRunner.java:167) at java.util.concurrent.FutureTask.run(FutureTask.java:262) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:744) -- CONFIDENTIALITY NOTICE NOTICE: This message is intended for the use of the individual or entity to which it is addressed and may contain information that is confidential, privileged and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any printing, copying, dissemination, distribution, disclosure or forwarding of this communication is strictly prohibited. If you have received this communication in error, please contact the sender immediately and delete it from your system. Thank You.
