[jira] [Created] (SPARK-7708) Incorrect task serialization with Kryo closure serializer

["Akshat Aranya (JIRA)" <ji...@apache.org>]

Akshat Aranya created SPARK-7708:
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             Summary: Incorrect task serialization with Kryo closure serializer
                 Key: SPARK-7708
                 URL: https://issues.apache.org/jira/browse/SPARK-7708
             Project: Spark
          Issue Type: Bug
          Components: Spark Core
    Affects Versions: 1.2.2
            Reporter: Akshat Aranya


I've been investigating the use of Kryo for closure serialization with Spark 1.2, and it seems like I've hit upon a bug:

When a task is serialized before scheduling, the following log message is generated:

[info] o.a.s.s.TaskSetManager - Starting task 124.1 in stage 0.0 (TID 342, <host>, PROCESS_LOCAL, 302 bytes)

This message comes from TaskSetManager which serializes the task using the closure serializer.  Before the message is sent out, the TaskDescription (which included the original task as a byte array), is serialized again into a byte array with the closure serializer.  I added a log message for this in CoarseGrainedSchedulerBackend, which produces the following output:

[info] o.a.s.s.c.CoarseGrainedSchedulerBackend - 124.1 size=132

The serialized size of TaskDescription (132 bytes) turns out to be _smaller_ than serialized task that it contains (302 bytes). This implies that TaskDescription.buffer is not getting serialized correctly.

On the executor side, the deserialization produces a null value for TaskDescription.buffer.



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