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https://issues.apache.org/jira/browse/BEAM-5775?focusedWorklogId=226562&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-226562
 ]

ASF GitHub Bot logged work on BEAM-5775:
----------------------------------------

                Author: ASF GitHub Bot
            Created on: 12/Apr/19 10:03
            Start Date: 12/Apr/19 10:03
    Worklog Time Spent: 10m 
      Work Description: iemejia commented on pull request #6714: [BEAM-5775] 
Spark: implement a custom class to lazily encode values for persistence.
URL: https://github.com/apache/beam/pull/6714#discussion_r274826081
 
 

 ##########
 File path: 
runners/spark/src/main/java/org/apache/beam/runners/spark/translation/GroupCombineFunctions.java
 ##########
 @@ -182,119 +176,4 @@
         .map(TranslationUtils.fromPairFunction())
         .map(TranslationUtils.toKVByWindowInValue());
   }
-
-  /**
-   * Wrapper around accumulated (combined) value with custom lazy 
serialization. Serialization is
-   * done through given coder and it is performed within on-serialization 
callbacks {@link
-   * #writeObject(ObjectOutputStream)} and {@link 
KryoAccumulatorSerializer#write(Kryo, Output,
-   * SerializableAccumulator)}. Both Spark's serialization mechanisms (Java 
Serialization, Kryo) are
-   * supported. Materialization of accumulated value is done when value is 
requested to avoid
-   * serialization of the coder itself.
-   *
-   * @param <AccumT>
-   */
-  public static class SerializableAccumulator<AccumT> implements Serializable {
 
 Review comment:
   Huge +1
 
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Issue Time Tracking
-------------------

    Worklog Id:     (was: 226562)
    Time Spent: 9h  (was: 8h 50m)

> Make the spark runner not serialize data unless spark is spilling to disk
> -------------------------------------------------------------------------
>
>                 Key: BEAM-5775
>                 URL: https://issues.apache.org/jira/browse/BEAM-5775
>             Project: Beam
>          Issue Type: Improvement
>          Components: runner-spark
>            Reporter: Mike Kaplinskiy
>            Assignee: Mike Kaplinskiy
>            Priority: Minor
>              Labels: triaged
>          Time Spent: 9h
>  Remaining Estimate: 0h
>
> Currently for storage level MEMORY_ONLY, Beam does not coder-ify the data. 
> This lets Spark keep the data in memory avoiding the serialization round 
> trip. Unfortunately the logic is fairly coarse - as soon as you switch to 
> MEMORY_AND_DISK, Beam coder-ifys the data even though Spark might have chosen 
> to keep the data in memory, incurring the serialization overhead.
>  
> Ideally Beam would serialize the data lazily - as Spark chooses to spill to 
> disk. This would be a change in behavior when using beam, but luckily Spark 
> has a solution for folks that want data serialized in memory - 
> MEMORY_AND_DISK_SER will keep the data serialized.



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