[SPARK-3086] [SPARK-3043] [SPARK-3156] [mllib]  DecisionTree aggregation improvements

Summary:
1. Variable numBins for each feature [SPARK-3043]
2. Reduced data reshaping in aggregation [SPARK-3043]
3. Choose ordering for ordered categorical features adaptively [SPARK-3156]
4. Changed nodes to use 1-indexing [SPARK-3086]
5. Small clean-ups

Note: This PR looks bigger than it is since I moved several functions from inside findBestSplitsPerGroup to outside of it (to make it clear what was being serialized in the aggregation).

Speedups: This update helps most when many features use few bins but a few features use many bins.  Some example results on speedups with 2M examples, 3.5K features (15-worker EC2 cluster):
* Example where old code was reasonably efficient (1/2 continuous, 1/4 binary, 1/4 20-category): 164.813 --> 116.491 sec
* Example where old code wasted many bins (1/10 continuous, 81/100 binary, 9/100 20-category): 128.701 --> 39.334 sec

Details:

(1) Variable numBins for each feature [SPARK-3043]

DecisionTreeMetadata now computes a variable numBins for each feature.  It also tracks numSplits.

(2) Reduced data reshaping in aggregation [SPARK-3043]

Added DTStatsAggregator, a wrapper around the aggregate statistics array for easy but efficient indexing.
* Added ImpurityAggregator and ImpurityCalculator classes, to make DecisionTree code more oblivious to the type of impurity.
* Design note: I originally tried creating Impurity classes which stored data and storing the aggregates in an Array[Array[Array[Impurity]]].  However, this led to significant slowdowns, perhaps because of overhead in creating so many objects.

The aggregate statistics are never reshaped, and cumulative sums are computed in-place.

Updated the layout of aggregation functions.  The update simplifies things by (1) dividing features into ordered/unordered (instead of ordered/unordered/continuous) and (2) making use of the DTStatsAggregator for indexing.
For this update, the following functions were refactored:
* updateBinForOrderedFeature
* updateBinForUnorderedFeature
* binaryOrNotCategoricalBinSeqOp
* multiclassWithCategoricalBinSeqOp
* regressionBinSeqOp
The above 5 functions were replaced with:
* orderedBinSeqOp
* someUnorderedBinSeqOp

Other changes:
* calculateGainForSplit now treats all feature types the same way.
* Eliminated extractLeftRightNodeAggregates.

(3) Choose ordering for ordered categorical features adaptively [SPARK-3156]

Updated binsToBestSplit():
* This now computes cumulative sums of stats for ordered features.
* For ordered categorical features, it chooses an ordering for categories. (This uses to be done by findSplitsBins.)
* Uses iterators to shorten code and avoid building an Array[Array[InformationGainStats]].

Side effects:
* In findSplitsBins: A sample of the data is only taken for data with continuous features.  It is not needed for data with only categorical features.
* In findSplitsBins: splits and bins are no longer pre-computed for ordered categorical features since they are not needed.
* TreePoint binning is simpler for categorical features.

(4) Changed nodes to use 1-indexing [SPARK-3086]

Nodes used to be indexed from 0.  Now they are indexed from 1.
Node indexing functions are now collected in object Node (Node.scala).

(5) Small clean-ups

Eliminated functions extractNodeInfo() and extractInfoForLowerLevels() to reduce duplicate code.
Eliminated InvalidBinIndex since it is no longer used.

CC: mengxr  manishamde  Please let me know if you have thoughts on this—thanks!

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

Closes #2125 from jkbradley/dt-opt3alt and squashes the following commits:

42c192a [Joseph K. Bradley] Merge branch 'rfs' into dt-opt3alt
d3cc46b [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt3alt
00e4404 [Joseph K. Bradley] optimization for TreePoint construction (pre-computing featureArity and isUnordered as arrays)
425716c [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into rfs
a2acea5 [Joseph K. Bradley] Small optimizations based on profiling
aa4e4df [Joseph K. Bradley] Updated DTStatsAggregator with bug fix (nodeString should not be multiplied by statsSize)
4651154 [Joseph K. Bradley] Changed numBins semantics for unordered features. * Before: numBins = numSplits = (1 << k - 1) - 1 * Now: numBins = 2 * numSplits = 2 * [(1 << k - 1) - 1] * This also involved changing the semantics of: ** DecisionTreeMetadata.numUnorderedBins()
1e3b1c7 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt3alt
1485fcc [Joseph K. Bradley] Made some DecisionTree methods private.
92f934f [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt3alt
e676da1 [Joseph K. Bradley] Updated documentation for DecisionTree
37ca845 [Joseph K. Bradley] Fixed problem with how DecisionTree handles ordered categorical	features.
105f8ab [Joseph K. Bradley] Removed commented-out getEmptyBinAggregates from DecisionTree
062c31d [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt3alt
6d32ccd [Joseph K. Bradley] In DecisionTree.binsToBestSplit, changed loops to iterators to shorten code.
807cd00 [Joseph K. Bradley] Finished DTStatsAggregator, a wrapper around the aggregate statistics for easy but hopefully efficient indexing.  Modified old ImpurityAggregator classes and renamed them ImpurityCalculator; added ImpurityAggregator classes which work with DTStatsAggregator but do not store data.  Unit tests all succeed.
f2166fd [Joseph K. Bradley] still working on DTStatsAggregator
92f7118 [Joseph K. Bradley] Added partly written DTStatsAggregator
fd8df30 [Joseph K. Bradley] Moved some aggregation helpers outside of findBestSplitsPerGroup
d7c53ee [Joseph K. Bradley] Added more doc for ImpurityAggregator
a40f8f1 [Joseph K. Bradley] Changed nodes to be indexed from 1.  Tests work.
95cad7c [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt3
5f94342 [Joseph K. Bradley] Added treeAggregate since not yet merged from master.  Moved node indexing functions to Node.
61c4509 [Joseph K. Bradley] Fixed bugs from merge: missing DT timer call, and numBins setting.  Cleaned up DT Suite some.
3ba7166 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt3
b314659 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt3
9c83363 [Joseph K. Bradley] partial merge but not done yet
45f7ea7 [Joseph K. Bradley] partial merge, not yet done
5fce635 [Joseph K. Bradley] Merge branch 'dt-opt2' into dt-opt3
26d10dd [Joseph K. Bradley] Removed tree/model/Filter.scala since no longer used.  Removed debugging println calls in DecisionTree.scala.
356daba [Joseph K. Bradley] Merge branch 'dt-opt1' into dt-opt2
430d782 [Joseph K. Bradley] Added more debug info on binning error.  Added some docs.
d036089 [Joseph K. Bradley] Print timing info to logDebug.
e66f1b1 [Joseph K. Bradley] TreePoint * Updated doc * Made some methods private
8464a6e [Joseph K. Bradley] Moved TimeTracker to tree/impl/ in its own file, and cleaned it up.  Removed debugging println calls from DecisionTree.  Made TreePoint extend Serialiable
a87e08f [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt1
dd4d3aa [Joseph K. Bradley] Mid-process in bug fix: bug for binary classification with categorical features * Bug: Categorical features were all treated as ordered for binary classification.  This is possible but would require the bin ordering to be determined on-the-fly after the aggregation.  Currently, the ordering is determined a priori and fixed for all splits. * (Temp) Fix: Treat low-arity categorical features as unordered for binary classification. * Related change: I removed most tests for isMulticlass in the code.  I instead test metadata for whether there are unordered features. * Status: The bug may be fixed, but more testing needs to be done.
438a660 [Joseph K. Bradley] removed subsampling for mnist8m from DT
86e217f [Joseph K. Bradley] added cache to DT input
e3c84cc [Joseph K. Bradley] Added stuff fro mnist8m to D T Runner
51ef781 [Joseph K. Bradley] Fixed bug introduced by last commit: Variance impurity calculation was incorrect since counts were swapped accidentally
fd65372 [Joseph K. Bradley] Major changes: * Created ImpurityAggregator classes, rather than old aggregates. * Feature split/bin semantics are based on ordered vs. unordered ** E.g.: numSplits = numBins for all unordered features, and numSplits = numBins - 1 for all ordered features. * numBins can differ for each feature
c1565a5 [Joseph K. Bradley] Small DecisionTree updates: * Simplification: Updated calculateGainForSplit to take aggregates for a single (feature, split) pair. * Internal doc: findAggForOrderedFeatureClassification
b914f3b [Joseph K. Bradley] DecisionTree optimization: eliminated filters + small changes
b2ed1f3 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-opt
0f676e2 [Joseph K. Bradley] Optimizations + Bug fix for DecisionTree
3211f02 [Joseph K. Bradley] Optimizing DecisionTree * Added TreePoint representation to avoid calling findBin multiple times. * (not working yet, but debugging)
f61e9d2 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
bcf874a [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
511ec85 [Joseph K. Bradley] Merge remote-tracking branch 'upstream/master' into dt-timing
a95bc22 [Joseph K. Bradley] timing for DecisionTree internals
SPARK-3337 Paranoid quoting in shell to allow install dirs with spaces within.

...

Tested ! TBH, it isn't a great idea to have directory with spaces within. Because emacs doesn't like it then hadoop doesn't like it. and so on...

Author: Prashant Sharma <prashant.s@imaginea.com>

Closes #2229 from ScrapCodes/SPARK-3337/quoting-shell-scripts and squashes the following commits:

d4ad660 [Prashant Sharma] SPARK-3337 Paranoid quoting in shell to allow install dirs with spaces within.
SPARK-2978. Transformation with MR shuffle semantics

I didn't add this to the transformations list in the docs because it's kind of obscure, but would be happy to do so if others think it would be helpful.

Author: Sandy Ryza <sandy@cloudera.com>

Closes #2274 from sryza/sandy-spark-2978 and squashes the following commits:

4a5332a [Sandy Ryza] Fix Java test
c04b447 [Sandy Ryza] Fix Python doc and add back deleted code
433ad5b [Sandy Ryza] Add Java test
4c25a54 [Sandy Ryza] Add s at the end and a couple other fixes
9b0ba99 [Sandy Ryza] Fix compilation
36e0571 [Sandy Ryza] Fix import ordering
48c12c2 [Sandy Ryza] Add Java version and additional doc
e5381cd [Sandy Ryza] Fix python style warnings
f147634 [Sandy Ryza] SPARK-2978. Transformation with MR shuffle semantics
Provide a default PYSPARK_PYTHON for python/run_tests

Without this the version of python used in the test is not
recorded. The error is,

   Testing with Python version:
   ./run-tests: line 57: --version: command not found

Author: Matthew Farrellee <matt@redhat.com>

Closes #2300 from mattf/master-fix-python-run-tests and squashes the following commits:

65a09f5 [Matthew Farrellee] Provide a default PYSPARK_PYTHON for python/run_tests
[SQL] Minor edits to sql programming guide.

Author: Henry Cook <hcook@eecs.berkeley.edu>

Closes #2316 from hcook/sql-docs and squashes the following commits:

373f94b [Henry Cook] Minor edits to sql programming guide.
[SPARK-3417] Use new-style classes in PySpark

Tiny PR making SQLContext a new-style class.  This allows various type logic to work more effectively

```Python
In [1]: import pyspark

In [2]: pyspark.sql.SQLContext.mro()
Out[2]: [pyspark.sql.SQLContext, object]
```

Author: Matthew Rocklin <mrocklin@gmail.com>

Closes #2288 from mrocklin/sqlcontext-new-style-class and squashes the following commits:

4aadab6 [Matthew Rocklin] update other old-style classes
a2dc02f [Matthew Rocklin] pyspark.sql.SQLContext is new-style class
[SPARK-3019] Pluggable block transfer interface (BlockTransferService)

This pull request creates a new BlockTransferService interface for block fetch/upload and refactors the existing ConnectionManager to implement BlockTransferService (NioBlockTransferService).

Most of the changes are simply moving code around. The main class to inspect is ShuffleBlockFetcherIterator.

Review guide:
- Most of the ConnectionManager code is now in network.cm package
- ManagedBuffer is a new buffer abstraction backed by several different implementations (file segment, nio ByteBuffer, Netty ByteBuf)
- BlockTransferService is the main internal interface introduced in this PR
- NioBlockTransferService implements BlockTransferService and replaces the old BlockManagerWorker
- ShuffleBlockFetcherIterator replaces the told BlockFetcherIterator to use the new interface

TODOs that should be separate PRs:
- Implement NettyBlockTransferService
- Finalize the API/semantics for ManagedBuffer.release()

Author: Reynold Xin <rxin@apache.org>

Closes #2240 from rxin/blockTransferService and squashes the following commits:

64cd9d7 [Reynold Xin] Merge branch 'master' into blockTransferService
1dfd3d7 [Reynold Xin] Limit the length of the FileInputStream.
1332156 [Reynold Xin] Fixed style violation from refactoring.
2960c93 [Reynold Xin] Added ShuffleBlockFetcherIteratorSuite.
e29c721 [Reynold Xin] Updated comment for ShuffleBlockFetcherIterator.
8a1046e [Reynold Xin] Code review feedback:
2c6b1e1 [Reynold Xin] Removed println in test cases.
2a907e4 [Reynold Xin] Merge branch 'master' into blockTransferService-merge
07ccf0d [Reynold Xin] Added init check to CMBlockTransferService.
98c668a [Reynold Xin] Added failure handling and fixed unit tests.
ae05fcd [Reynold Xin] Updated tests, although DistributedSuite is hanging.
d8d595c [Reynold Xin] Merge branch 'master' of github.com:apache/spark into blockTransferService
9ef279c [Reynold Xin] Initial refactoring to move ConnectionManager to use the BlockTransferService.
[SPARK-3349][SQL] Output partitioning of limit should not be inherited from child

This resolves https://issues.apache.org/jira/browse/SPARK-3349

Author: Eric Liang <ekl@google.com>

Closes #2262 from ericl/spark-3349 and squashes the following commits:

3e1b05c [Eric Liang] add regression test
ac32723 [Eric Liang] make limit/takeOrdered output SinglePartition
[SPARK-3443][MLLIB] update default values of tree:

Adjust the default values of decision tree, based on the memory requirement discussed in https://github.com/apache/spark/pull/2125 :

1. maxMemoryInMB: 128 -> 256
2. maxBins: 100 -> 32
3. maxDepth: 4 -> 5 (in some example code)

jkbradley

Author: Xiangrui Meng <meng@databricks.com>

Closes #2322 from mengxr/tree-defaults and squashes the following commits:

cda453a [Xiangrui Meng] fix tests
5900445 [Xiangrui Meng] update comments
8c81831 [Xiangrui Meng] update default values of tree:
SPARK-3423:  [SQL] Implement BETWEEN for SQLParser

This patch improves the SQLParser by adding support for BETWEEN conditions

Author: William Benton <willb@redhat.com>

Closes #2295 from willb/sql-between and squashes the following commits:

0016d30 [William Benton] Implement BETWEEN for SQLParser
[SPARK-3414][SQL] Stores analyzed logical plan when registering a temp table

Case insensitivity breaks when unresolved relation contains attributes with uppercase letters in their names, because we store unanalyzed logical plan when registering temp tables while the `CaseInsensitivityAttributeReferences` batch runs before the `Resolution` batch. To fix this issue, we need to store analyzed logical plan.

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

Closes #2293 from liancheng/spark-3414 and squashes the following commits:

d9fa1d6 [Cheng Lian] Stores analyzed logical plan when registering a temp table
[SPARK-3329][SQL] Don't depend on Hive SET pair ordering in tests.

This fixes some possible spurious test failures in `HiveQuerySuite` by comparing sets of key-value pairs as sets, rather than as lists.

Author: William Benton <willb@redhat.com>
Author: Aaron Davidson <aaron@databricks.com>

Closes #2220 from willb/spark-3329 and squashes the following commits:

3b3e205 [William Benton] Collapse collectResults case match in HiveQuerySuite
6525d8e [William Benton] Handle cases where SET returns Rows of (single) strings
cf11b0e [Aaron Davidson] Fix flakey HiveQuerySuite test
SPARK-2425 Don't kill a still-running Application because of some misbehaving Executors

Introduces a LOADING -> RUNNING ApplicationState transition and prevents Master from removing an Application with RUNNING Executors.

Two basic changes: 1) Instead of allowing MAX_NUM_RETRY abnormal Executor exits over the entire lifetime of the Application, allow that many since any Executor successfully began running the Application; 2) Don't remove the Application while Master still thinks that there are RUNNING Executors.

This should be fine as long as the ApplicationInfo doesn't believe any Executors are forever RUNNING when they are not.  I think that any non-RUNNING Executors will eventually no longer be RUNNING in Master's accounting, but another set of eyes should confirm that.  This PR also doesn't try to detect which nodes have gone rogue or to kill off bad Workers, so repeatedly failing Executors will continue to fail and fill up log files with failure reports as long as the Application keeps running.

Author: Mark Hamstra <markhamstra@gmail.com>

Closes #1360 from markhamstra/SPARK-2425 and squashes the following commits:

f099c0b [Mark Hamstra] Reuse appInfo
b2b7b25 [Mark Hamstra] Moved 'Application failed' logging
bdd0928 [Mark Hamstra] switched to string interpolation
1dd591b [Mark Hamstra] SPARK-2425 introduce LOADING -> RUNNING ApplicationState transition and prevent Master from removing Application with RUNNING Executors
[Build] Removed -Phive-thriftserver since this profile has been removed

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

Closes #2269 from liancheng/clean-run-tests-profile and squashes the following commits:

08617bd [Cheng Lian] Removed -Phive-thriftserver since this profile has been removed
[Docs] actorStream storageLevel default is MEMORY_AND_DISK_SER_2

Comment of the storageLevel param of actorStream says that it defaults to memory-only while the default is MEMORY_AND_DISK_SER_2.

Author: Mario Pastorelli <pastorelli.mario@gmail.com>

Closes #2319 from melrief/master and squashes the following commits:

7b6ce68 [Mario Pastorelli] [Docs] actorStream storageLevel default is MEMORY_AND_DISK_SER_2