[jira] [Created] (SPARK-16746) Spark streaming lost data when ReceiverTracker writes Blockinfo to hdfs timeout

["Hongyao Zhao (JIRA)" <ji...@apache.org>]

Hongyao Zhao created SPARK-16746:
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             Summary: Spark streaming lost data when ReceiverTracker writes Blockinfo to hdfs timeout
                 Key: SPARK-16746
                 URL: https://issues.apache.org/jira/browse/SPARK-16746
             Project: Spark
          Issue Type: Bug
          Components: Streaming
    Affects Versions: 1.6.1
            Reporter: Hongyao Zhao
            Priority: Minor


I wrote a spark streaming program which consume 1000 messages from one topic of Kafka, did some transformation, and wrote the result back to another topic. But only found 988 messages in the second topic. I checked log info and confirmed all messages was received by receivers. But I found a hdfs writing time out message printed from Class BatchedWriteAheadLog. 
    
    I checkout source code and found code like this: 
  
```
    /** Add received block. This event will get written to the write ahead log (if enabled). */ 
  def addBlock(receivedBlockInfo: ReceivedBlockInfo): Boolean = { 
    try { 
      val writeResult = writeToLog(BlockAdditionEvent(receivedBlockInfo)) 
      if (writeResult) { 
        synchronized { 
          getReceivedBlockQueue(receivedBlockInfo.streamId) += receivedBlockInfo 
        } 
        logDebug(s"Stream ${receivedBlockInfo.streamId} received " + 
          s"block ${receivedBlockInfo.blockStoreResult.blockId}") 
      } else { 
        logDebug(s"Failed to acknowledge stream ${receivedBlockInfo.streamId} receiving " + 
          s"block ${receivedBlockInfo.blockStoreResult.blockId} in the Write Ahead Log.") 
      } 
      writeResult 
    } catch { 
      case NonFatal(e) => 
        logError(s"Error adding block $receivedBlockInfo", e) 
        false 
    } 
  } 
```
    
    It seems that ReceiverTracker tries to write block info to hdfs, but the write operation time out, this cause writeToLog function return false, and  this code "getReceivedBlockQueue(receivedBlockInfo.streamId) += receivedBlockInfo" is skipped. so the block info is lost. 

   The spark version I use is 1.6.1 and I did not turn on spark.streaming.receiver.writeAheadLog.enable. 
    
   I want to know whether or not this is a designed behaviour. 



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