[SPARK-7351][Streaming][Docs] Add spark.streaming.ui.retainedBatches to docs

[zsxwing]

The default value will be changed to 1000 in #5533. So here I just used 1000.

[SparkQA]

Test build #31805 has finished for PR 5899 at commit e1ec515.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds no public classes.

[zsxwing]

retest this please.

[SparkQA]

Test build #31807 has finished for PR 5899 at commit e1ec515.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • abstract class ShuffleHandle(val shuffleId: Int) extends Serializable
  • * class SomethingNotSerializable
  • logDebug(s" + cloning the object $obj of class $
  • abstract class Evaluator extends Params
  • abstract class PipelineStage extends Params with Logging
  • class BinaryClassificationEvaluator extends Evaluator with HasRawPredictionCol with HasLabelCol
  • trait LDAOptimizer
  • class EMLDAOptimizer extends LDAOptimizer
  • class OnlineLDAOptimizer extends LDAOptimizer
  • class SaslEncryption
  • static class EncryptedMessage extends AbstractReferenceCounted implements FileRegion
  • class SaslRpcHandler extends RpcHandler
  • public class SaslServerBootstrap implements TransportServerBootstrap
  • public class SparkSaslClient implements SaslEncryptionBackend
  • public class SparkSaslServer implements SaslEncryptionBackend
  • public class ByteArrayWritableChannel implements WritableByteChannel
  • class ParamGridBuilder(object):
  • abstract class Dialect
  • class DialectException(msg: String, cause: Throwable) extends Exception(msg, cause)
  • case class HiveDatabase(
  • abstract class TableType
  • case class HiveStorageDescriptor(
  • case class HivePartition(
  • case class HiveColumn(name: String, hiveType: String, comment: String)
  • case class HiveTable(
  • trait ClientInterface
  • class ClientWrapper(
  • class IsolatedClientLoader(
  • protected trait ReflectionMagic
  • protected implicit class InstanceMagic(a: Any)
  • protected implicit class StaticMagic(c: Class[_])

[srowen]

I think the only question is whether this was intended to be exposed to users or not. What's your argument for that? This should be 100, and changed to 1000 in your other PR if this goes in.

[zsxwing]

This is just like spark.ui.retainedJobs and spark.ui.retainedStages and should be exposed. I think we can merge this after #5533.

[zsxwing]

#5533 is merged. So this one is ready to go.

[tdas]

LGTM. Merging.