[SPARK-17125][SPARKR] Allow to specify spark config using non-string type in SparkR

[zjffdu]

What changes were proposed in this pull request?

Allow to set spark configuration using non-string type in sparkR

How was this patch tested?

Tested manually using the following command

sparkR.session(master="yarn-client", sparkConfig = list(spark.executor.instances=1))

[SparkQA]

Test build #63981 has finished for PR 14699 at commit 5540366.

• This patch fails SparkR unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[felixcheung]

Your example was failing for a different reason:

Error in invokeJava(isStatic = TRUE, className, methodName, ...) : 
  java.lang.IllegalArgumentException: spark.executor.instances should be int, but was 1.0

Means that your 1 is being interpreted as numeric instead of integer.
This works:

sparkR.session(master="yarn-client", sparkConfig = list(spark.executor.instances=1L))

[zjffdu]

Make sense, @felixcheung Thanks

[felixcheung]

I haven't exhaustively test out configs, not sure always coercing to string might be limiting, in certain cases (eg. user was expecting 1 -> 1.0 (numeric) but now 1 -> "1" (character)

[zjffdu]

@felixcheung In what of case user was expecting 1 -> 1.0 (numeric), because internally SparkConf use string for both key and value.

[felixcheung]

It's hard to say. Right now it is being converted on the JVM side - so it is possible to have 1 -> 1.0 -> "1.0"
Also convertNamedListToEnv are being in several other cases that seem to expect numeric type - could you check that?

[felixcheung]

would you like to follow up or close this?