chenghao-intel assigned this to me, check PR #2284 for previous discussion

Author: Daoyuan Wang <daoyuan.wang@intel.com>

Closes #2529 from adrian-wang/rowapi and squashes the following commits:

c6594b2 [Daoyuan Wang] using boxed
7b7e6e3 [Daoyuan Wang] update pattern match
7a39456 [Daoyuan Wang] rename file and refresh getAs[T]
4c18c29 [Daoyuan Wang] remove setAs[T] and null judge
1614493 [Daoyuan Wang] add missing row api

This PR aims to provide a way to skip/query corrupt JSON records. To do so, we introduce an internal column to hold corrupt records (the default name is `_corrupt_record`. This name can be changed by setting the value of `spark.sql.columnNameOfCorruptRecord`). When there is a parsing error, we will put the corrupt record in its unparsed format to the internal column. Users can skip/query this column through SQL.

* To query those corrupt records
```
-- For Hive parser
SELECT `_corrupt_record`
FROM jsonTable
WHERE `_corrupt_record` IS NOT NULL
-- For our SQL parser
SELECT _corrupt_record
FROM jsonTable
WHERE _corrupt_record IS NOT NULL
```
* To skip corrupt records and query regular records
```
-- For Hive parser
SELECT field1, field2
FROM jsonTable
WHERE `_corrupt_record` IS NULL
-- For our SQL parser
SELECT field1, field2
FROM jsonTable
WHERE _corrupt_record IS NULL
```

Generally, it is not recommended to change the name of the internal column. If the name has to be changed to avoid possible name conflicts, you can use `sqlContext.setConf(SQLConf.COLUMN_NAME_OF_CORRUPT_RECORD, <new column name>)` or `sqlContext.sql(SET spark.sql.columnNameOfCorruptRecord=<new column name>)`.

Author: Yin Huai <huai@cse.ohio-state.edu>

Closes #2680 from yhuai/corruptJsonRecord and squashes the following commits:

4c9828e [Yin Huai] Merge remote-tracking branch 'upstream/master' into corruptJsonRecord
309616a [Yin Huai] Change the default name of corrupt record to "_corrupt_record".
b4a3632 [Yin Huai] Merge remote-tracking branch 'upstream/master' into corruptJsonRecord
9375ae9 [Yin Huai] Set the column name of corrupt json record back to the default one after the unit test.
ee584c0 [Yin Huai] Provide a way to query corrupt json records as unparsed strings.

This reverts commit b9df8af6.

In JSONRDD.scala, add 'case TimestampType' in the enforceCorrectType function and a toTimestamp function.

Author: Mike Timper <mike@aurorafeint.com>

Closes #2720 from mtimper/master and squashes the following commits:

9386ab8 [Mike Timper] Fix and tests for SPARK-3853

./python/run-tests script display messages about which test it is running currently on stdout but not write them on unit-tests.log.
It is harder for us to recognize what test programs were executed and which test was failed.

Author: cocoatomo <cocoatomo77@gmail.com>

Closes #2724 from cocoatomo/issues/3868-display-testing-module-name and squashes the following commits:

c63d9fa [cocoatomo] [SPARK-3868][PySpark] Hard to recognize which module is tested from unit-tests.log

To fix two issues in CliSuite
1 CliSuite throw IndexOutOfBoundsException:
Exception in thread "Thread-6" java.lang.IndexOutOfBoundsException: 6
	at scala.collection.mutable.ResizableArray$class.apply(ResizableArray.scala:43)
	at scala.collection.mutable.ArrayBuffer.apply(ArrayBuffer.scala:47)
	at org.apache.spark.sql.hive.thriftserver.CliSuite.org$apache$spark$sql$hive$thriftserver$CliSuite$$captureOutput$1(CliSuite.scala:67)
	at org.apache.spark.sql.hive.thriftserver.CliSuite$$anonfun$4.apply(CliSuite.scala:78)
	at org.apache.spark.sql.hive.thriftserver.CliSuite$$anonfun$4.apply(CliSuite.scala:78)
	at scala.sys.process.ProcessLogger$$anon$1.out(ProcessLogger.scala:96)
	at scala.sys.process.BasicIO$$anonfun$processOutFully$1.apply(BasicIO.scala:135)
	at scala.sys.process.BasicIO$$anonfun$processOutFully$1.apply(BasicIO.scala:135)
	at scala.sys.process.BasicIO$.readFully$1(BasicIO.scala:175)
	at scala.sys.process.BasicIO$.processLinesFully(BasicIO.scala:179)
	at scala.sys.process.BasicIO$$anonfun$processFully$1.apply(BasicIO.scala:164)
	at scala.sys.process.BasicIO$$anonfun$processFully$1.apply(BasicIO.scala:162)
	at scala.sys.process.ProcessBuilderImpl$Simple$$anonfun$3.apply$mcV$sp(ProcessBuilderImpl.scala:73)
	at scala.sys.process.ProcessImpl$Spawn$$anon$1.run(ProcessImpl.scala:22)

Actually, it is the Mutil-Threads lead to this problem.

2 Using ```line.startsWith``` instead ```line.contains``` to assert expected answer. This is a tiny bug in CliSuite, for test case "Simple commands", there is a expected answers "5", if we use ```contains``` that means output like "14/10/06 11:```5```4:36 INFO CliDriver: Time taken: 1.078 seconds" or "14/10/06 11:54:36 INFO StatsReportListener: 	0%	```5```%	10%	25%	50%	75%	90%	95%	100%" will make the assert true.

Author: scwf <wangfei1@huawei.com>

Closes #2666 from scwf/clisuite and squashes the following commits:

11430db [scwf] fix-clisuite

The In case class is replaced by a InSet class in case all the filters are literals, which uses a hashset instead of Sequence, thereby giving significant performance improvement (earlier the seq was using a worst case linear match (exists method) since expressions were assumed in the filter list) . Maximum improvement should be visible in case small percentage of large data matches the filter list.

Author: Yash Datta <Yash.Datta@guavus.com>

Closes #2561 from saucam/branch-1.1 and squashes the following commits:

4bf2d19 [Yash Datta] SPARK-3711: 1. Fix code style and import order             2. Fix optimization condition             3. Add tests for null in filter list             4. Add test case that optimization is not triggered in case of attributes in filter list
afedbcd [Yash Datta] SPARK-3711: 1. Add test cases for InSet class in ExpressionEvaluationSuite             2. Add class OptimizedInSuite on the lines of ConstantFoldingSuite, for the optimized In clause
0fc902f [Yash Datta] SPARK-3711: UnaryMinus will be handled by constantFolding
bd84c67 [Yash Datta] SPARK-3711: Incorporate review comments. Move optimization of In clause to Optimizer.scala by adding a rule. Add appropriate comments
430f5d1 [Yash Datta] SPARK-3711: Optimize the filter list in case of negative values as well
bee98aa [Yash Datta] SPARK-3711: Optimize where in clause filter queries

Author: Vida Ha <vida@databricks.com>

Closes #2621 from vidaha/vida/SPARK-3752 and squashes the following commits:

d7fdbbc [Vida Ha] Add tests for different UDF's

...re logs to avoid Executors swallowing errors

This PR made the following changes:
* Register a callback to `Connection` so that the error will be propagated properly.
* Add more logs so that the errors won't be swallowed by Executors.
* Use trySuccess/tryFailure because `Promise` doesn't allow to call success/failure more than once.

Author: zsxwing <zsxwing@gmail.com>

Closes #2593 from zsxwing/SPARK-3741 and squashes the following commits:

1d5aed5 [zsxwing] Fix naming
0b8a61c [zsxwing] Merge branch 'master' into SPARK-3741
764aec5 [zsxwing] [SPARK-3741] Make ConnectionManager propagate errors properly and add more logs to avoid Executors swallowing errors

cc mengxr

Author: GuoQiang Li <witgo@qq.com>

Closes #2730 from witgo/SPARK-3856 and squashes the following commits:

2cffce1 [GuoQiang Li] use norm operator after breeze 0.10 upgrade

Currently, the implementation does one unnecessary aggregation step. The aggregation step for level L (to choose splits) gives enough information to set the predictions of any leaf nodes at level L+1. We can use that info and skip the aggregation step for the last level of the tree (which only has leaf nodes).

### Implementation Details

Each node now has a `impurity` field and the `predict` is changed from type `Double` to type `Predict`(this can be used to compute predict probability in the future) When compute best splits for each node, we also compute impurity and predict for the child nodes, which is used to constructed newly allocated child nodes. So at level L, we have set impurity and predict for nodes at level L +1.
If level L+1 is the last level, then we can avoid aggregation. What's more, calculation of parent impurity in

Top nodes for each tree needs to be treated differently because we have to compute impurity and predict for them first. In `binsToBestSplit`, if current node is top node(level == 0), we calculate impurity and predict first.
after finding best split, top node's predict and impurity is set to the calculated value. Non-top nodes's impurity and predict are already calculated and don't need to be recalculated again. I have considered to add a initialization step to set top nodes' impurity and predict and then we can treat all nodes in the same way, but this will need a lot of duplication of code(all the code to do seq operation(BinSeqOp) needs to be duplicated), so I choose the current way.

 CC mengxr manishamde jkbradley, please help me review this, thanks.

Author: Qiping Li <liqiping1991@gmail.com>

Closes #2708 from chouqin/avoid-agg and squashes the following commits:

8e269ea [Qiping Li] adjust code and comments
eefeef1 [Qiping Li] adjust comments and check child nodes' impurity
c41b1b6 [Qiping Li] fix pyspark unit test
7ad7a71 [Qiping Li] fix unit test
822c912 [Qiping Li] add comments and unit test
e41d715 [Qiping Li] fix bug in test suite
6cc0333 [Qiping Li] SPARK-3158: Avoid 1 extra aggregation for DecisionTree training

It took me a minute to track this down, so I thought it could be useful to have it in the docs.

I'm unsure if 512mb is the default for spark.driver.memory? Also - there could be a better value for the 'description' to differentiate it from spark.executor.memory.

Author: nartz <nartzpod@gmail.com>
Author: Nathan Artz <nathanartz@Nathans-MacBook-Pro.local>

Closes #2410 from nartz/docs/add-spark-driver-memory-to-config-docs and squashes the following commits:

a2f6c62 [nartz] Update configuration.md
74521b8 [Nathan Artz] add spark.driver.memory to config docs

Truncate appName in WebUI if it is too long.

Author: Xiangrui Meng <meng@databricks.com>

Closes #2707 from mengxr/truncate-app-name and squashes the following commits:

87834ce [Xiangrui Meng] move scala import below java
c7111dc [Xiangrui Meng] truncate appName in WebUI if it is too long

Upgrade to akka 2.3.4

Author: Anand Avati <avati@redhat.com>

Closes #1685 from avati/SPARK-1812-akka-2.3 and squashes the following commits:

57a2315 [Anand Avati] SPARK-1812: streaming - remove tests which depend on akka.actor.IO
2a551d3 [Anand Avati] SPARK-1812: core - upgrade to akka 2.3.4

Got warning msg:

~~~
[warn] /Users/meng/src/spark/mllib/src/main/scala/org/apache/spark/mllib/feature/Normalizer.scala:50: method norm in trait NumericOps is deprecated: Use norm(XXX) instead of XXX.norm
[warn]     var norm = vector.toBreeze.norm(p)
~~~

dbtsai

Author: Xiangrui Meng <meng@databricks.com>

Closes #2718 from mengxr/SPARK-3856 and squashes the following commits:

4f38169 [Xiangrui Meng] use norm operator

Author: Reynold Xin <rxin@apache.org>

Closes #2719 from rxin/sql-join-break and squashes the following commits:

0c0082b [Reynold Xin] Fix line length.
cbc664c [Reynold Xin] Rename join -> joins package.
a070d44 [Reynold Xin] Fix line length in HashJoin
a39be8c [Reynold Xin] [SPARK-3857] Create a join package for various join operators.

Builds all wrappers at first according to object inspector types to avoid per row costs.

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #2592 from liancheng/hive-value-wrapper and squashes the following commits:

9696559 [Cheng Lian] Passes all tests
4998666 [Cheng Lian] Prevents per row dynamic dispatching and pattern matching when inserting Hive values

Includes partition keys into account when applying `PreInsertionCasts` rule.

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #2672 from liancheng/fix-pre-insert-casts and squashes the following commits:

def1a1a [Cheng Lian] Makes PreInsertionCasts handle partitions properly

Calling `BinaryArithmetic.dataType` will throws exception until it's resolved, but in type coercion rule `Division`, seems doesn't follow this.

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

Closes #2559 from chenghao-intel/type_coercion and squashes the following commits:

199a85d [Cheng Hao] Simplify the divide rule
dc55218 [Cheng Hao] fix bug of type coercion in div

marmbrus
Update README.md to be consistent with Spark 1.1

Author: Liquan Pei <liquanpei@gmail.com>

Closes #2706 from Ishiihara/SparkSQL-readme and squashes the following commits:

33b9d4b [Liquan Pei] keep README.md up to date

This PR uses JSON instead of `toString` to serialize `DataType`s. The latter is not only hard to parse but also flaky in many cases.

Since we already write schema information to Parquet metadata in the old style, we have to reserve the old `DataType` parser and ensure downward compatibility. The old parser is now renamed to `CaseClassStringParser` and moved into `object DataType`.

JoshRosen davies Please help review PySpark related changes, thanks!

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #2563 from liancheng/datatype-to-json and squashes the following commits:

fc92eb3 [Cheng Lian] Reverts debugging code, simplifies primitive type JSON representation
438c75f [Cheng Lian] Refactors PySpark DataType JSON SerDe per comments
6b6387b [Cheng Lian] Removes debugging code
6a3ee3a [Cheng Lian] Addresses per review comments
dc158b5 [Cheng Lian] Addresses PEP8 issues
99ab4ee [Cheng Lian] Adds compatibility est case for Parquet type conversion
a983a6c [Cheng Lian] Adds PySpark support
f608c6e [Cheng Lian] De/serializes DataType objects from/to JSON

If we write the filter which is always FALSE like

    SELECT * from person WHERE FALSE;

200 tasks will run. I think, 1 task is enough.

And current optimizer cannot optimize the case NOT is duplicated like

    SELECT * from person WHERE NOT ( NOT (age > 30));

The filter rule above should be simplified

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2692 from sarutak/SPARK-3831 and squashes the following commits:

25f3e20 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into SPARK-3831
23c750c [Kousuke Saruta] Improved unsupported predicate test case
a11b9f3 [Kousuke Saruta] Modified NOT predicate test case in PartitionBatchPruningSuite
8ea872b [Kousuke Saruta] Fixed the number of tasks when the data of  LocalRelation is empty.

dev/scalastyle create a log file 'scalastyle.txt'. it is overwrote per running but never deleted even though dev/mima and dev/lint-python delete their log files.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2702 from sarutak/scalastyle-txt-cleanup and squashes the following commits:

d6e238e [Kousuke Saruta] Fixed dev/scalastyle to cleanup scalastyle.txt

Provide a parent class for the Params case classes used in many MLlib examples, where the parent class pretty-prints the case class fields:
Param1Name	Param1Value
Param2Name	Param2Value
...
Using this class will make it easier to print test settings to logs.

Also, updated DecisionTreeRunner to print a little more info.

CC: mengxr

Author: Joseph K. Bradley <joseph.kurata.bradley@gmail.com>

Closes #2700 from jkbradley/dtrunner-update and squashes the following commits:

cff873f [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dtrunner-update
7a08ae4 [Joseph K. Bradley] code review comment updates
b4d2043 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dtrunner-update
d8228a7 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dtrunner-update
0fc9c64 [Joseph K. Bradley] Added abstract TestParams class for mllib example parameters
12b7798 [Joseph K. Bradley] Added abstract class TestParams for pretty-printing Params values
5f84f03 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dtrunner-update
f7441b6 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dtrunner-update
19eb6fc [Joseph K. Bradley] Updated DecisionTreeRunner to print training time.

yarn alpha build was broken by #2432
as it added an argument to YarnAllocator but not to yarn/alpha YarnAllocationHandler
commit https://github.com/apache/spark/commit/79e45c9323455a51f25ed9acd0edd8682b4bbb88

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2715 from sarutak/SPARK-3848 and squashes the following commits:

bafb8d1 [Kousuke Saruta] Fixed parameters for the default constructor of alpha/YarnAllocatorHandler.

HA and viewfs use namespaces instead of host names, so you can't
resolve them since that will fail. So be smarter to avoid doing
unnecessary work.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #2649 from vanzin/SPARK-3788 and squashes the following commits:

fedbc73 [Marcelo Vanzin] Update comment.
c938845 [Marcelo Vanzin] Use Objects.equal() to avoid issues with ==.
9f7b571 [Marcelo Vanzin] [SPARK-3788] [yarn] Fix compareFs to do the right thing for HA, federation.

It seems some dependencies are not declared when pulling the 2.2
test dependencies, so we need to add them manually for the Yarn
cluster to come up.

These don't seem to be necessary for 2.3 and beyond, so restrict
them to the hadoop-2.2 profile.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #2682 from vanzin/SPARK-3710 and squashes the following commits:

701d4fb [Marcelo Vanzin] Add comment.
0540bdf [Marcelo Vanzin] [SPARK-3710] Fix Yarn integration tests on Hadoop 2.2.

Optionally have the repl throw exceptions generated by interpreted code, instead of swallowing the exception and returning it as text output. This is useful when embedding the repl, otherwise it's not possible to know when user code threw an exception.

Author: Ahir Reddy <ahirreddy@gmail.com>

Closes #2695 from ahirreddy/repl-throw-exceptions and squashes the following commits:

bad25ee [Ahir Reddy] Style Fixes
f0e5b44 [Ahir Reddy] Fixed style
0d4413d [Ahir Reddy] propogate excetions from repl

Retire Epydoc, use Sphinx to generate API docs.

Refine Sphinx docs, also convert some docstrings into Sphinx style.

It looks like:
![api doc](https://cloud.githubusercontent.com/assets/40902/4538272/9e2d4f10-4dec-11e4-8d96-6e45a8fe51f9.png)

Author: Davies Liu <davies.liu@gmail.com>

Closes #2689 from davies/docs and squashes the following commits:

bf4a0a5 [Davies Liu] fix links
3fb1572 [Davies Liu] fix _static in jekyll
65a287e [Davies Liu] fix scripts and logo
8524042 [Davies Liu] Merge branch 'master' of github.com:apache/spark into docs
d5b874a [Davies Liu] Merge branch 'master' of github.com:apache/spark into docs
4bc1c3c [Davies Liu] refactor
746d0b6 [Davies Liu] @param -> :param
240b393 [Davies Liu] replace epydoc with sphinx doc

There is a Spark logo on the header of HistoryPage.
We can have too many HistoryPages if we run 20+ applications. So I think, it's useful if the logo is as a link to the HistoryPage's page number 1.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2690 from sarutak/SPARK-3829 and squashes the following commits:

908c109 [Kousuke Saruta] Removed extra space.
00bfbd7 [Kousuke Saruta] Merge branch 'master' of git://git.apache.org/spark into SPARK-3829
dd87480 [Kousuke Saruta] Made header Spark log image as a link to History Server's top page.

Instead of waiting arbitrary amounts of time for the cluster to reach a specific state, this patch lets `spark-ec2` explicitly wait for a cluster to reach a desired state.

This is useful in a couple of situations:
* The cluster is launching and you want to wait until SSH is available before installing stuff.
* The cluster is being terminated and you want to wait until all the instances are terminated before trying to delete security groups.

This patch removes the need for the `--wait` option and removes some of the time-based retry logic that was being used.

Author: Nicholas Chammas <nicholas.chammas@gmail.com>

Closes #2339 from nchammas/spark-ec2-wait-properly and squashes the following commits:

43a69f0 [Nicholas Chammas] short-circuit SSH check; linear backoff
9a9e035 [Nicholas Chammas] remove extraneous comment
26c5ed0 [Nicholas Chammas] replace print with write()
bb67c06 [Nicholas Chammas] deprecate wait option; remove dead code
7969265 [Nicholas Chammas] fix long line (PEP 8)
126e4cf [Nicholas Chammas] wait for specific cluster states

In Breeze 0.10, the L1regParam can be configured through anonymous function in OWLQN, and each component can be penalized differently. This is required for GLMNET in MLlib with L1/L2 regularization.
https://github.com/scalanlp/breeze/commit/2570911026aa05aa1908ccf7370bc19cd8808a4c

Author: DB Tsai <dbtsai@dbtsai.com>

Closes #2693 from dbtsai/breeze0.10 and squashes the following commits:

7a0c45c [DB Tsai] In Breeze 0.10, the L1regParam can be configured through anonymous function in OWLQN, and each component can be penalized differently. This is required for GLMNET in MLlib with L1/L2 regularization. https://github.com/scalanlp/breeze/commit/2570911026aa05aa1908ccf7370bc19cd8808a4c

mengxr
Added PySpark support for Word2Vec
Change list
(1) PySpark support for Word2Vec
(2) SerDe support of string sequence both on python side and JVM side
(3) Test for SerDe of string sequence on JVM side

Author: Liquan Pei <liquanpei@gmail.com>

Closes #2356 from Ishiihara/Word2Vec-python and squashes the following commits:

476ea34 [Liquan Pei] style fixes
b13a0b9 [Liquan Pei] resolve merge conflicts and minor fixes
8671eba [Liquan Pei] Merge remote-tracking branch 'upstream/master' into Word2Vec-python
daf88a6 [Liquan Pei] modification according to feedback
a73fa19 [Liquan Pei] clean up
3d8007b [Liquan Pei] fix findSynonyms for vector
1bdcd2e [Liquan Pei] minor fixes
cdef9f4 [Liquan Pei] add missing comments
b7447eb [Liquan Pei] modify according to feedback
b9a7383 [Liquan Pei] cache words RDD in fit
89490bf [Liquan Pei] add tests and Word2VecModelWrapper
78bbb53 [Liquan Pei] use pickle for seq string SerDe
a264b08 [Liquan Pei] Merge remote-tracking branch 'upstream/master' into Word2Vec-python
ca1e5ff [Liquan Pei] fix test
68e7276 [Liquan Pei] minor style fixes
48d5e72 [Liquan Pei] Functionality improvement
0ad3ac1 [Liquan Pei] minor fix
c867fdf [Liquan Pei] add Word2Vec to pyspark

Provide example  for `RowMatrix.columnSimilarity()`

Author: Reza Zadeh <rizlar@gmail.com>

Closes #2622 from rezazadeh/dimsumexample and squashes the following commits:

8f20b82 [Reza Zadeh] update comment
379066d [Reza Zadeh] cache rows
792b81c [Reza Zadeh] Address review comments
e573c7a [Reza Zadeh] Average absolute error
b15685f [Reza Zadeh] Use scopt. Distribute evaluation.
eca3dfd [Reza Zadeh] Documentation
ac96fb2 [Reza Zadeh] Compute approximation error, add command line.
4533579 [Reza Zadeh] CosineSimilarity Example

Now the Stage page only displays "Executor"(host) for tasks. However, there may be more than one Executors running in the same host. Currently, when some task is hung, I only know the host of the faulty executor. Therefore I have to check all executors in the host.

Adding "Executor ID" in the Tasks table. would be helpful to locate the faulty executor. Here is the new page:

![add_executor_id_for_tasks](https://cloud.githubusercontent.com/assets/1000778/4505774/acb9648c-4afa-11e4-8826-8768a0a60cc9.png)

Author: zsxwing <zsxwing@gmail.com>

Closes #2642 from zsxwing/SPARK-3777 and squashes the following commits:

37945af [zsxwing] Put Executor ID and Host into one cell
4bbe2c7 [zsxwing] [SPARK-3777] Display "Executor ID" for Tasks in Stage page

Before:
```
14/10/06 16:45:42 WARN CacheManager: Not enough space to cache partition rdd_0_2
in memory! Free memory is 481861527 bytes.
```
After:
```
14/10/07 11:08:24 WARN MemoryStore: Not enough space to cache rdd_2_0 in memory!
(computed 68.8 MB so far)
14/10/07 11:08:24 INFO MemoryStore: Memory use = 1088.0 B (blocks) + 445.1 MB
(scratch space shared across 8 thread(s)) = 445.1 MB. Storage limit = 459.5 MB.
```

Author: Andrew Or <andrewor14@gmail.com>

Closes #2688 from andrewor14/cache-log-message and squashes the following commits:

28e33d6 [Andrew Or] Shy away from "unrolling"
5638c49 [Andrew Or] Grammar
39a0c28 [Andrew Or] Log more detail when unrolling a block fails

The parent.getOrCompute() of PythonRDD is executed in a separated thread, it should release the memory reserved for shuffle and unrolling finally.

Author: Davies Liu <davies.liu@gmail.com>

Closes #2668 from davies/leak and squashes the following commits:

ae98be2 [Davies Liu] fix memory leak in PythonRDD

SparkEnv is cached in ThreadLocal object, so after stop and create a new SparkContext, old SparkEnv is still used by some threads, it will trigger many problems, for example, pyspark will have problem after restart SparkContext, because py4j use thread pool for RPC.

This patch will clear all the references after stop a SparkEnv.

cc mateiz tdas pwendell

Author: Davies Liu <davies.liu@gmail.com>

Closes #2624 from davies/env and squashes the following commits:

a69f30c [Davies Liu] deprecate getThreadLocal
ba77ca4 [Davies Liu] remove getThreadLocal(), update docs
ee62bb7 [Davies Liu] cleanup ThreadLocal of SparnENV
4d0ea8b [Davies Liu] clear reference of SparkEnv after stop