[jira] [Created] (SPARK-7139) Allow received block metadata to be saved to WAL and recovered on driver failure

["Tathagata Das (JIRA)" <ji...@apache.org>]

Tathagata Das created SPARK-7139:
------------------------------------

             Summary: Allow received block metadata to be saved to WAL and recovered on driver failure
                 Key: SPARK-7139
                 URL: https://issues.apache.org/jira/browse/SPARK-7139
             Project: Spark
          Issue Type: Improvement
          Components: Streaming
            Reporter: Tathagata Das
            Assignee: Tathagata Das
            Priority: Critical


The received API allows arbitrary metadata to be added for each block. However that information is not saved in the WAL as part of the block information in the driver. 

To fix this, the following needs to be done. 

1. Forward the metadata to the ReceivedBlockTracker in the driver.
2. ReceivedBlockTracker saves the metadata and recovers it on restart. 

However there is one tricky thing. The ReceivedBlockTracker WAL is enabled only when `spark.streaming.receiver.writeAheadLog.enable = true`. This means that only when  receiver WAL is enabled is the driver WAL enabled. This is not desired as the one may want to save and recovered block metadata information (especially information like Kafka offsets or Kinesis sequence numbers) that can be used to recover data without actually saving the data to the receiver WAL. So we have to always enable the tracker WAL. 

3. Always enable the ReceivedBlockTracker WAL. However, make sure that the blockIds are not recovered as they will not be useful after driver restart (the blocks are gone!). 



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org