Spark 1916

The changes could be ported back to 0.9 as well.
Changing in.read to in.readFully to read the whole input stream rather than the first 1020 bytes.
This should ok considering that Flume caps the body size to 32K by default.

Author: David Lemieux <david.lemieux@radialpoint.com>

Closes #865 from lemieud/SPARK-1916 and squashes the following commits:

a265673 [David Lemieux] Updated SparkFlumeEvent to read the whole stream rather than the first X bytes.
(cherry picked from commit 0b769b73fb7ae314325857138a2d3138ed157908)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
[SPARK-1712]: TaskDescription instance is too big causes Spark to hang

Author: witgo <witgo@qq.com>

Closes #694 from witgo/SPARK-1712_new and squashes the following commits:

0f52483 [witgo] review commit
83ce29b [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
52e6752 [witgo] reset test SparkContext
63636b6 [witgo] review commit
44a59ee [witgo] review commit
3b6d48c [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
926bd6a [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
9a5cfad [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
03cc562 [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
b0930b0 [witgo] review commit
b1174bd [witgo] merge master
f76679b [witgo] merge master
689495d [witgo] fix scala style bug
1d35c3c [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
062c182 [witgo] fix small bug for code style
0a428cf [witgo] add unit tests
158b2dc [witgo] review commit
4afe71d [witgo] review commit
9e4ffa7 [witgo] review commit
1d35c7d [witgo] fix hang
7965580 [witgo] fix Statement order
0e29eac [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
3ea1ca1 [witgo] remove duplicate serialize
743a7ad [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
86e2048 [witgo] Merge branch 'master' of https://github.com/apache/spark into SPARK-1712_new
2a89adc [witgo] SPARK-1712: TaskDescription instance is too big causes Spark to hang

Conflicts:
	core/src/main/scala/org/apache/spark/executor/CoarseGrainedExecutorBackend.scala
	core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala
SPARK-1188: Do not re-use objects in the EdgePartition/EdgeTriplet iterators.

This avoids a silent data corruption issue (https://spark-project.atlassian.net/browse/SPARK-1188) and has no performance impact by my measurements. It also simplifies the code. As far as I can tell the object re-use was nothing but premature optimization.

I did actual benchmarks for all the included changes, and there is no performance difference. I am not sure where to put the benchmarks. Does Spark not have a benchmark suite?

This is an example benchmark I did:

test("benchmark") {
  val builder = new EdgePartitionBuilder[Int]
  for (i <- (1 to 10000000)) {
    builder.add(i.toLong, i.toLong, i)
  }
  val p = builder.toEdgePartition
  p.map(_.attr + 1).iterator.toList
}

It ran for 10 seconds both before and after this change.

Author: Daniel Darabos <darabos.daniel@gmail.com>

Closes #276 from darabos/spark-1188 and squashes the following commits:

574302b [Daniel Darabos] Restore "manual" copying in EdgePartition.map(Iterator). Add comment to discourage novices like myself from trying to simplify the code.
4117a64 [Daniel Darabos] Revert EdgePartitionSuite.
4955697 [Daniel Darabos] Create a copy of the Edge objects in EdgeRDD.compute(). This avoids exposing the object re-use, while still enables the more efficient behavior for internal code.
4ec77f8 [Daniel Darabos] Add comments about object re-use to the affected functions.
2da5e87 [Daniel Darabos] Restore object re-use in EdgePartition.
0182f2b [Daniel Darabos] Do not re-use objects in the EdgePartition/EdgeTriplet iterators. This avoids a silent data corruption issue (SPARK-1188) and has no performance impact in my measurements. It also simplifies the code.
c55f52f [Daniel Darabos] Tests that reproduce the problems from SPARK-1188.

(cherry picked from commit 78236334e4ca7518b6d7d9b38464dbbda854a777)
Signed-off-by: Reynold Xin <rxin@apache.org>