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From Aaron Davidson <>
Subject Re: Spark unit test question
Date Mon, 21 Oct 2013 20:06:06 GMT
To answer your second question first, you can use the SparkContext format
"local-cluster[2, 1, 512]" (instead of "local[2]"), which would create a
local test cluster with 2 workers, each with 1 core and 512 MB of memory.
This should allow you to accurately test things like serialization.

I don't believe that adding a function-local variable would cause the
function to be unserializable, though. The only concern when shipping
around functions is when they refer to variables *outside* the function's
scope, in which case Spark will automatically ship those variables to all
workers (unless you override this behavior with a broadcast or accumulator

On Mon, Oct 21, 2013 at 10:30 AM, Shay Seng <> wrote:

> I'm trying to write a unit test to ensure that some functions I rely on
> will always serialize and run correctly on a cluster.
> In one of these functions I've deliberately added a "val x:Int = 1" which
> should prevent this method from being serializable right?
> In the test I've done:
>    sc = new SparkContext("local[2]","test")
>    ...
>    val pdata = sc.parallelize(data)
>    val c =
> The unit tests still complete with no errors; I'm guessing because spark
> knows that local[2] doesn't require serialization? Is there someway I can
> force spark to run like it would do on a real cluster?
> tks
> shay

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