[maven-release-plugin] prepare release spark-parent-0.9.2-candidate-csd-6
[maven-release-plugin] prepare for next development iteration
SPARK-1990: added compatibility for python 2.6 for ssh_read command

https://issues.apache.org/jira/browse/SPARK-1990

There were some posts on the lists that spark-ec2 does not work with Python 2.6. In addition, we should check the Python version at the top of the script and exit if it's too old

Author: Anant <anant.asty@gmail.com>

Closes #941 from anantasty/SPARK-1990 and squashes the following commits:

4ca441d [Anant] Implmented check_optput withinthe module to work with python 2.6
c6ed85c [Anant] added compatibility for python 2.6 for ssh_read command

Conflicts:

	ec2/spark_ec2.py
HOTFIX: bug caused by #941

This patch should have qualified the use of PIPE. This needs to be back ported into 0.9 and 1.0.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #1108 from pwendell/hotfix and squashes the following commits:

711c58d [Patrick Wendell] HOTFIX: bug caused by #941

(cherry picked from commit b2ebf429e24566c29850c570f8d76943151ad78c)
Signed-off-by: Xiangrui Meng <meng@databricks.com>
SPARK-2241: quote command line args in ec2 script

To preserve quoted command line args (in case options have space in them).

Author: Ori Kremer <ori.kremer@gmail.com>

Closes #1169 from orikremer/quote_cmd_line_args and squashes the following commits:

67e2aa1 [Ori Kremer] quote command line args
(cherry picked from commit 9fc373e3a9a8ba7bea9df0950775f48918f63a8a)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
[SPARK-1912] fix compress memory issue during reduce

When we need to read a compressed block, we will first create a compress stream instance(LZF or Snappy) and use it to wrap that block.
Let's say a reducer task need to read 1000 local shuffle blocks, it will first prepare to read that 1000 blocks, which means create 1000 compression stream instance to wrap them. But the initialization of compression instance will allocate some memory and when we have many compression instance at the same time, it is a problem.
Actually reducer reads the shuffle blocks one by one, so we can do the compression instance initialization lazily.

Author: Wenchen Fan(Cloud) <cloud0fan@gmail.com>

Closes #860 from cloud-fan/fix-compress and squashes the following commits:

0924a6b [Wenchen Fan(Cloud)] rename 'doWork' into 'getIterator'
07f32c2 [Wenchen Fan(Cloud)] move the LazyProxyIterator to dataDeserialize
d80c426 [Wenchen Fan(Cloud)] remove empty lines in short class
2c8adb2 [Wenchen Fan(Cloud)] add inline comment
8ebff77 [Wenchen Fan(Cloud)] fix compress memory issue during reduce
Merge branch 'branch-0.9' of github.com:apache/spark into master-csd