SPARK-1746: Support setting SPARK_JAVA_OPTS on executors for backwards compatibility

Author: Patrick Wendell <pwendell@gmail.com>

Closes #676 from pwendell/worker-opts and squashes the following commits:

54456c4 [Patrick Wendell] SPARK-1746: Support setting SPARK_JAVA_OPTS on executors for backwards compatibility
[WIP][Spark-SQL] Optimize the Constant Folding for Expression

Currently, expression does not support the "constant null" well in constant folding.
e.g. Sum(a, 0) actually always produces Literal(0, NumericType) in runtime.

For example:
```
explain select isnull(key+null)  from src;
== Logical Plan ==
Project [HiveGenericUdf#isnull((key#30 + CAST(null, IntegerType))) AS c_0#28]
 MetastoreRelation default, src, None

== Optimized Logical Plan ==
Project [true AS c_0#28]
 MetastoreRelation default, src, None

== Physical Plan ==
Project [true AS c_0#28]
 HiveTableScan [], (MetastoreRelation default, src, None), None
```

I've create a new Optimization rule called NullPropagation for such kind of constant folding.

Author: Cheng Hao <hao.cheng@intel.com>
Author: Michael Armbrust <michael@databricks.com>

Closes #482 from chenghao-intel/optimize_constant_folding and squashes the following commits:

2f14b50 [Cheng Hao] Fix code style issues
68b9fad [Cheng Hao] Remove the Literal pattern matching for NullPropagation
29c8166 [Cheng Hao] Update the code for feedback of code review
50444cc [Cheng Hao] Remove the unnecessary null checking
80f9f18 [Cheng Hao] Update the UnitTest for aggregation constant folding
27ea3d7 [Cheng Hao] Fix Constant Folding Bugs & Add More Unittests
b28e03a [Cheng Hao] Merge pull request #1 from marmbrus/pr/482
9ccefdb [Michael Armbrust] Add tests for optimized expression evaluation.
543ef9d [Cheng Hao] fix code style issues
9cf0396 [Cheng Hao] update code according to the code review comment
536c005 [Cheng Hao] Add Exceptional case for constant folding
3c045c7 [Cheng Hao] Optimize the Constant Folding by adding more rules
2645d4f [Cheng Hao] Constant Folding(null propagation)
[SPARK-1460] Returning SchemaRDD instead of normal RDD on Set operations...

... that do not change schema

Author: Kan Zhang <kzhang@apache.org>

Closes #448 from kanzhang/SPARK-1460 and squashes the following commits:

111e388 [Kan Zhang] silence MiMa errors in EdgeRDD and VertexRDD
91dc787 [Kan Zhang] Taking into account newly added Ordering param
79ed52a [Kan Zhang] [SPARK-1460] Returning SchemaRDD on Set operations that do not change schema
SPARK-1579: Clean up PythonRDD and avoid swallowing IOExceptions

This patch includes several cleanups to PythonRDD, focused around fixing [SPARK-1579](https://issues.apache.org/jira/browse/SPARK-1579) cleanly. Listed in order of approximate importance:

- The Python daemon waits for Spark to close the socket before exiting,
  in order to avoid causing spurious IOExceptions in Spark's
  `PythonRDD::WriterThread`.
- Removes the Python Monitor Thread, which polled for task cancellations
  in order to kill the Python worker. Instead, we do this in the
  onCompleteCallback, since this is guaranteed to be called during
  cancellation.
- Adds a "completed" variable to TaskContext to avoid the issue noted in
  [SPARK-1019](https://issues.apache.org/jira/browse/SPARK-1019), where onCompleteCallbacks may be execution-order dependent.
  Along with this, I removed the "context.interrupted = true" flag in
  the onCompleteCallback.
- Extracts PythonRDD::WriterThread to its own class.

Since this patch provides an alternative solution to [SPARK-1019](https://issues.apache.org/jira/browse/SPARK-1019), I did test it with

```
sc.textFile("latlon.tsv").take(5)
```

many times without error.

Additionally, in order to test the unswallowed exceptions, I performed

```
sc.textFile("s3n://<big file>").count()
```

and cut my internet during execution. Prior to this patch, we got the "stdin writer exited early" message, which was unhelpful. Now, we get the SocketExceptions propagated through Spark to the user and get proper (though unsuccessful) task retries.

Author: Aaron Davidson <aaron@databricks.com>

Closes #640 from aarondav/pyspark-io and squashes the following commits:

b391ff8 [Aaron Davidson] Detect "clean socket shutdowns" and stop waiting on the socket
c0c49da [Aaron Davidson] SPARK-1579: Clean up PythonRDD and avoid swallowing IOExceptions
[SQL] Fix Performance Issue in data type casting

Using lazy val object instead of function in the class Cast, which improved the performance nearly by 2X in my local micro-benchmark.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #679 from chenghao-intel/fix_type_casting and squashes the following commits:

71b0902 [Cheng Hao] using lazy val object instead of function for data type casting
Nicer logging for SecurityManager startup

Happy to open a jira ticket if you'd like to track one there.

Author: Andrew Ash <andrew@andrewash.com>

Closes #678 from ash211/SecurityManagerLogging and squashes the following commits:

2aa0b7a [Andrew Ash] Nicer logging for SecurityManager startup
Typo fix: fetchting -> fetching

Author: Andrew Ash <andrew@andrewash.com>

Closes #680 from ash211/patch-3 and squashes the following commits:

9ce3746 [Andrew Ash] Typo fix: fetchting -> fetching
[SPARK-1688] Propagate PySpark worker stderr to driver

When at least one of the following conditions is true, PySpark cannot be loaded:

1. PYTHONPATH is not set
2. PYTHONPATH does not contain the python directory (or jar, in the case of YARN)
3. The jar does not contain pyspark files (YARN)
4. The jar does not contain py4j files (YARN)

However, we currently throw the same random `java.io.EOFException` for all of the above cases, when trying to read from the python daemon's output. This message is super unhelpful.

This PR includes the python stderr and the PYTHONPATH in the exception propagated to the driver. Now, the exception message looks something like:

```
Error from python worker:
  : No module named pyspark
PYTHONPATH was:
  /path/to/spark/python:/path/to/some/jar
java.io.EOFException
  <stack trace>
```

whereas before it was just

```
java.io.EOFException
  <stack trace>
```

Author: Andrew Or <andrewor14@gmail.com>

Closes #603 from andrewor14/pyspark-exception and squashes the following commits:

10d65d3 [Andrew Or] Throwable -> Exception, worker -> daemon
862d1d7 [Andrew Or] Merge branch 'master' of github.com:apache/spark into pyspark-exception
a5ed798 [Andrew Or] Use block string and interpolation instead of var (minor)
cc09c45 [Andrew Or] Account for the fact that the python daemon may not have terminated yet
444f019 [Andrew Or] Use the new RedirectThread + include system PYTHONPATH
aab00ae [Andrew Or] Merge branch 'master' of github.com:apache/spark into pyspark-exception
0cc2402 [Andrew Or] Merge branch 'master' of github.com:apache/spark into pyspark-exception
783efe2 [Andrew Or] Make python daemon stderr indentation consistent
9524172 [Andrew Or] Avoid potential NPE / error stream contention + Move things around
29f9688 [Andrew Or] Add back original exception type
e92d36b [Andrew Or] Include python worker stderr in the exception propagated to the driver
7c69360 [Andrew Or] Merge branch 'master' of github.com:apache/spark into pyspark-exception
cdbc185 [Andrew Or] Fix python attribute not found exception when PYTHONPATH is not set
dcc0353 [Andrew Or] Check both python and system environment variables for PYTHONPATH
6c09c21 [Andrew Or] Validate PYTHONPATH and PySpark modules before starting python workers
update pyspark's SparseVector.__str__
add parse to pyspark's Vectors
add stringify to pyspark's Vectors
SPARK-1569 Spark on Yarn, authentication broken by pr299

Pass the configs as java options since the executor needs to know before it registers whether to create the connection using authentication or not.    We could see about passing only the authentication configs but for now I just had it pass them all.

I also updating it to use a list to construct the command to make it the same as ClientBase and avoid any issues with spaces.

Author: Thomas Graves <tgraves@apache.org>

Closes #649 from tgravescs/SPARK-1569 and squashes the following commits:

0178ab8 [Thomas Graves] add akka settings
22a8735 [Thomas Graves] Change to only path spark.auth* configs
8ccc1d4 [Thomas Graves] SPARK-1569 Spark on Yarn, authentication broken
[SPARK-1743][MLLIB] add loadLibSVMFile and saveAsLibSVMFile to pyspark

Make loading/saving labeled data easier for pyspark users.

Also changed type check in `SparseVector` to allow numpy integers.

Author: Xiangrui Meng <meng@databricks.com>

Closes #672 from mengxr/pyspark-mllib-util and squashes the following commits:

2943fa7 [Xiangrui Meng] format docs
d61668d [Xiangrui Meng] add loadLibSVMFile and saveAsLibSVMFile to pyspark
Update GradientDescentSuite.scala

use more faster way to construct an array

Author: baishuo(白硕) <vc_java@hotmail.com>

Closes #588 from baishuo/master and squashes the following commits:

45b95fb [baishuo(白硕)] Update GradientDescentSuite.scala
c03b61c [baishuo(白硕)] Update GradientDescentSuite.scala
b666d27 [baishuo(白硕)] Update GradientDescentSuite.scala
add __str__ and parse to LabeledPoint
Merge branch 'master' into labeled-io
add loadLabeledPoints to pyspark