[SPARK-2218] rename Equals to EqualTo in Spark SQL expressions.

Due to the existence of scala.Equals, it is very error prone to name the expression Equals, especially because we use a lot of partial functions and pattern matching in the optimizer.

Note that this sits on top of #1144.

Author: Reynold Xin <rxin@apache.org>

Closes #1146 from rxin/equals and squashes the following commits:

f8583fd [Reynold Xin] Merge branch 'master' of github.com:apache/spark into equals
326b388 [Reynold Xin] Merge branch 'master' of github.com:apache/spark into equals
bd19807 [Reynold Xin] Rename EqualsTo to EqualTo.
81148d1 [Reynold Xin] [SPARK-2218] rename Equals to EqualsTo in Spark SQL expressions.
c4e543d [Reynold Xin] [SPARK-2210] boolean cast on boolean value should be removed.
[SPARK-2163] class LBFGS optimize with Double tolerance instead of Int

https://issues.apache.org/jira/browse/SPARK-2163

This pull request includes the change for **[SPARK-2163]**:

* Changed the convergence tolerance parameter from type `Int` to type `Double`.
* Added types for vars in `class LBFGS`, making the style consistent with `class GradientDescent`.
* Added associated test to check that optimizing via `class LBFGS` produces the same results as via calling `runLBFGS` from `object LBFGS`.

This is a very minor change but it will solve the problem in my implementation of a regression model for count data, where I make use of LBFGS for parameter estimation.

Author: Gang Bai <me@baigang.net>

Closes #1104 from BaiGang/fix_int_tol and squashes the following commits:

cecf02c [Gang Bai] Changed setConvergenceTol'' to specify tolerance with a parameter of type Double. For the reason and the problem caused by an Int parameter, please check https://issues.apache.org/jira/browse/SPARK-2163. Added a test in LBFGSSuite for validating that optimizing via class LBFGS produces the same results as calling runLBFGS from object LBFGS. Keep the indentations and styles correct.
SPARK-1868: Users should be allowed to cogroup at least 4 RDDs

Adds cogroup for 4 RDDs.

Author: Allan Douglas R. de Oliveira <allandouglas@gmail.com>

Closes #813 from douglaz/more_cogroups and squashes the following commits:

f8d6273 [Allan Douglas R. de Oliveira] Test python groupWith for one more case
0e9009c [Allan Douglas R. de Oliveira] Added scala tests
c3ffcdd [Allan Douglas R. de Oliveira] Added java tests
517a67f [Allan Douglas R. de Oliveira] Added tests for python groupWith
2f402d5 [Allan Douglas R. de Oliveira] Removed TODO
17474f4 [Allan Douglas R. de Oliveira] Use new cogroup function
7877a2a [Allan Douglas R. de Oliveira] Fixed code
ba02414 [Allan Douglas R. de Oliveira] Added varargs cogroup to pyspark
c4a8a51 [Allan Douglas R. de Oliveira] Added java cogroup 4
e94963c [Allan Douglas R. de Oliveira] Fixed spacing
f1ee57b [Allan Douglas R. de Oliveira] Fixed scala style issues
d7196f1 [Allan Douglas R. de Oliveira] Allow the cogroup of 4 RDDs
SPARK-2180:  support HAVING clauses in Hive queries

This PR extends Spark's HiveQL support to handle HAVING clauses in aggregations.  The HAVING test from the Hive compatibility suite doesn't appear to be runnable from within Spark, so I added a simple comparable test to `HiveQuerySuite`.

Author: William Benton <willb@redhat.com>

Closes #1136 from willb/SPARK-2180 and squashes the following commits:

3bbaf26 [William Benton] Added casts to HAVING expressions
83f1340 [William Benton] scalastyle fixes
18387f1 [William Benton] Add test for HAVING without GROUP BY
b880bef [William Benton] Added semantic error for HAVING without GROUP BY
942428e [William Benton] Added test coverage for SPARK-2180.
56084cc [William Benton] Add support for HAVING clauses in Hive queries.
[SPARK-2225] Turn HAVING without GROUP BY into WHERE.

@willb

Author: Reynold Xin <rxin@apache.org>

Closes #1161 from rxin/having-filter and squashes the following commits:

fa8359a [Reynold Xin] [SPARK-2225] Turn HAVING without GROUP BY into WHERE.
Clean up CacheManager et al.

**UPDATE**

I have removed the special handling for `StorageLevel.MEMORY_*_SER` for now, because it introduces a potential performance regression. With the latest changes, this PR should include mainly style (code readability) fixes. The only functionality change is the update in `MemoryStore#putBytes` to actually return updated blocks, though this is a minor bug fix.

Now this is mainly a precursor to another PR (once again).

---------
*Old comment*

The deserialized version of a partition may occupy much more space than the serialized version. Therefore, if a partition is to be cached with `StorageLevel.MEMORY_*_SER`, we don't need to fully unroll it into an `ArrayBuffer`, but instead we can unroll it into a potentially much smaller `ByteBuffer`. This may save us from OOMs in this case.

Author: Andrew Or <andrewor14@gmail.com>

Closes #1083 from andrewor14/unroll-them-partitions and squashes the following commits:

7048aa0 [Andrew Or] Merge branch 'master' of github.com:apache/spark into unroll-them-partitions
3d9a366 [Andrew Or] Minor change for readability
d12b95f [Andrew Or] Remove unused imports (minor)
a4c387b [Andrew Or] Merge branch 'master' of github.com:apache/spark into unroll-them-partitions
cf5f565 [Andrew Or] Remove special handling for MEM_*_SER
0091ec0 [Andrew Or] Address review feedback
44ef282 [Andrew Or] Actually return updated blocks in putBytes
2941c89 [Andrew Or] Clean up BlockStore (minor)
a8f181d [Andrew Or] Add special handling for StorageLevel.MEMORY_*_SER
Move ScriptTransformation into the appropriate place.

Author: Reynold Xin <rxin@apache.org>

Closes #1162 from rxin/script and squashes the following commits:

2c836b9 [Reynold Xin] Move ScriptTransformation into the appropriate place.
[SQL] Use hive.SessionState, not the thread local SessionState

Note that this is simply mimicing lookupRelation(). I do not have a concrete notion of why this solution is necessarily right-er than SessionState.get, but SessionState.get is returning null, which is bad.

Author: Aaron Davidson <aaron@databricks.com>

Closes #1148 from aarondav/createtable and squashes the following commits:

37c3e7c [Aaron Davidson] [SQL] Use hive.SessionState, not the thread local SessionState
SPARK-1902 Silence stacktrace from logs when doing port failover to port n+1

Before:

```
14/06/08 23:58:23 WARN AbstractLifeCycle: FAILED SelectChannelConnector@0.0.0.0:4040: java.net.BindException: Address already in use
java.net.BindException: Address already in use
	at sun.nio.ch.Net.bind0(Native Method)
	at sun.nio.ch.Net.bind(Net.java:444)
	at sun.nio.ch.Net.bind(Net.java:436)
	at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:214)
	at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
	at org.eclipse.jetty.server.nio.SelectChannelConnector.open(SelectChannelConnector.java:187)
	at org.eclipse.jetty.server.AbstractConnector.doStart(AbstractConnector.java:316)
	at org.eclipse.jetty.server.nio.SelectChannelConnector.doStart(SelectChannelConnector.java:265)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
	at org.eclipse.jetty.server.Server.doStart(Server.java:293)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
	at org.apache.spark.ui.JettyUtils$$anonfun$1.apply$mcV$sp(JettyUtils.scala:192)
	at org.apache.spark.ui.JettyUtils$$anonfun$1.apply(JettyUtils.scala:192)
	at org.apache.spark.ui.JettyUtils$$anonfun$1.apply(JettyUtils.scala:192)
	at scala.util.Try$.apply(Try.scala:161)
	at org.apache.spark.ui.JettyUtils$.connect$1(JettyUtils.scala:191)
	at org.apache.spark.ui.JettyUtils$.startJettyServer(JettyUtils.scala:205)
	at org.apache.spark.ui.WebUI.bind(WebUI.scala:99)
	at org.apache.spark.SparkContext.<init>(SparkContext.scala:223)
	at org.apache.spark.repl.SparkILoop.createSparkContext(SparkILoop.scala:957)
	at $line3.$read$$iwC$$iwC.<init>(<console>:8)
	at $line3.$read$$iwC.<init>(<console>:14)
	at $line3.$read.<init>(<console>:16)
	at $line3.$read$.<init>(<console>:20)
	at $line3.$read$.<clinit>(<console>)
	at $line3.$eval$.<init>(<console>:7)
	at $line3.$eval$.<clinit>(<console>)
	at $line3.$eval.$print(<console>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.spark.repl.SparkIMain$ReadEvalPrint.call(SparkIMain.scala:788)
	at org.apache.spark.repl.SparkIMain$Request.loadAndRun(SparkIMain.scala:1056)
	at org.apache.spark.repl.SparkIMain.loadAndRunReq$1(SparkIMain.scala:614)
	at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:645)
	at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:609)
	at org.apache.spark.repl.SparkILoop.reallyInterpret$1(SparkILoop.scala:796)
	at org.apache.spark.repl.SparkILoop.interpretStartingWith(SparkILoop.scala:841)
	at org.apache.spark.repl.SparkILoop.command(SparkILoop.scala:753)
	at org.apache.spark.repl.SparkILoopInit$$anonfun$initializeSpark$1.apply(SparkILoopInit.scala:121)
	at org.apache.spark.repl.SparkILoopInit$$anonfun$initializeSpark$1.apply(SparkILoopInit.scala:120)
	at org.apache.spark.repl.SparkIMain.beQuietDuring(SparkIMain.scala:263)
	at org.apache.spark.repl.SparkILoopInit$class.initializeSpark(SparkILoopInit.scala:120)
	at org.apache.spark.repl.SparkILoop.initializeSpark(SparkILoop.scala:56)
	at org.apache.spark.repl.SparkILoop$$anonfun$process$1$$anonfun$apply$mcZ$sp$5.apply$mcV$sp(SparkILoop.scala:913)
	at org.apache.spark.repl.SparkILoopInit$class.runThunks(SparkILoopInit.scala:142)
	at org.apache.spark.repl.SparkILoop.runThunks(SparkILoop.scala:56)
	at org.apache.spark.repl.SparkILoopInit$class.postInitialization(SparkILoopInit.scala:104)
	at org.apache.spark.repl.SparkILoop.postInitialization(SparkILoop.scala:56)
	at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply$mcZ$sp(SparkILoop.scala:930)
	at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply(SparkILoop.scala:884)
	at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply(SparkILoop.scala:884)
	at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135)
	at org.apache.spark.repl.SparkILoop.process(SparkILoop.scala:884)
	at org.apache.spark.repl.SparkILoop.process(SparkILoop.scala:982)
	at org.apache.spark.repl.Main$.main(Main.scala:31)
	at org.apache.spark.repl.Main.main(Main.scala)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.spark.deploy.SparkSubmit$.launch(SparkSubmit.scala:292)
	at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:55)
	at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
14/06/08 23:58:23 WARN AbstractLifeCycle: FAILED org.eclipse.jetty.server.Server@7439e55a: java.net.BindException: Address already in use
java.net.BindException: Address already in use
	at sun.nio.ch.Net.bind0(Native Method)
	at sun.nio.ch.Net.bind(Net.java:444)
	at sun.nio.ch.Net.bind(Net.java:436)
	at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:214)
	at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
	at org.eclipse.jetty.server.nio.SelectChannelConnector.open(SelectChannelConnector.java:187)
	at org.eclipse.jetty.server.AbstractConnector.doStart(AbstractConnector.java:316)
	at org.eclipse.jetty.server.nio.SelectChannelConnector.doStart(SelectChannelConnector.java:265)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
	at org.eclipse.jetty.server.Server.doStart(Server.java:293)
	at org.eclipse.jetty.util.component.AbstractLifeCycle.start(AbstractLifeCycle.java:64)
	at org.apache.spark.ui.JettyUtils$$anonfun$1.apply$mcV$sp(JettyUtils.scala:192)
	at org.apache.spark.ui.JettyUtils$$anonfun$1.apply(JettyUtils.scala:192)
	at org.apache.spark.ui.JettyUtils$$anonfun$1.apply(JettyUtils.scala:192)
	at scala.util.Try$.apply(Try.scala:161)
	at org.apache.spark.ui.JettyUtils$.connect$1(JettyUtils.scala:191)
	at org.apache.spark.ui.JettyUtils$.startJettyServer(JettyUtils.scala:205)
	at org.apache.spark.ui.WebUI.bind(WebUI.scala:99)
	at org.apache.spark.SparkContext.<init>(SparkContext.scala:223)
	at org.apache.spark.repl.SparkILoop.createSparkContext(SparkILoop.scala:957)
	at $line3.$read$$iwC$$iwC.<init>(<console>:8)
	at $line3.$read$$iwC.<init>(<console>:14)
	at $line3.$read.<init>(<console>:16)
	at $line3.$read$.<init>(<console>:20)
	at $line3.$read$.<clinit>(<console>)
	at $line3.$eval$.<init>(<console>:7)
	at $line3.$eval$.<clinit>(<console>)
	at $line3.$eval.$print(<console>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.spark.repl.SparkIMain$ReadEvalPrint.call(SparkIMain.scala:788)
	at org.apache.spark.repl.SparkIMain$Request.loadAndRun(SparkIMain.scala:1056)
	at org.apache.spark.repl.SparkIMain.loadAndRunReq$1(SparkIMain.scala:614)
	at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:645)
	at org.apache.spark.repl.SparkIMain.interpret(SparkIMain.scala:609)
	at org.apache.spark.repl.SparkILoop.reallyInterpret$1(SparkILoop.scala:796)
	at org.apache.spark.repl.SparkILoop.interpretStartingWith(SparkILoop.scala:841)
	at org.apache.spark.repl.SparkILoop.command(SparkILoop.scala:753)
	at org.apache.spark.repl.SparkILoopInit$$anonfun$initializeSpark$1.apply(SparkILoopInit.scala:121)
	at org.apache.spark.repl.SparkILoopInit$$anonfun$initializeSpark$1.apply(SparkILoopInit.scala:120)
	at org.apache.spark.repl.SparkIMain.beQuietDuring(SparkIMain.scala:263)
	at org.apache.spark.repl.SparkILoopInit$class.initializeSpark(SparkILoopInit.scala:120)
	at org.apache.spark.repl.SparkILoop.initializeSpark(SparkILoop.scala:56)
	at org.apache.spark.repl.SparkILoop$$anonfun$process$1$$anonfun$apply$mcZ$sp$5.apply$mcV$sp(SparkILoop.scala:913)
	at org.apache.spark.repl.SparkILoopInit$class.runThunks(SparkILoopInit.scala:142)
	at org.apache.spark.repl.SparkILoop.runThunks(SparkILoop.scala:56)
	at org.apache.spark.repl.SparkILoopInit$class.postInitialization(SparkILoopInit.scala:104)
	at org.apache.spark.repl.SparkILoop.postInitialization(SparkILoop.scala:56)
	at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply$mcZ$sp(SparkILoop.scala:930)
	at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply(SparkILoop.scala:884)
	at org.apache.spark.repl.SparkILoop$$anonfun$process$1.apply(SparkILoop.scala:884)
	at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135)
	at org.apache.spark.repl.SparkILoop.process(SparkILoop.scala:884)
	at org.apache.spark.repl.SparkILoop.process(SparkILoop.scala:982)
	at org.apache.spark.repl.Main$.main(Main.scala:31)
	at org.apache.spark.repl.Main.main(Main.scala)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.spark.deploy.SparkSubmit$.launch(SparkSubmit.scala:292)
	at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:55)
	at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)
14/06/08 23:58:23 INFO JettyUtils: Failed to create UI at port, 4040. Trying again.
14/06/08 23:58:23 INFO JettyUtils: Error was: Failure(java.net.BindException: Address already in use)
14/06/08 23:58:23 INFO SparkUI: Started SparkUI at http://aash-mbp.local:4041
````

After:
```
14/06/09 00:04:12 INFO JettyUtils: Failed to create UI at port, 4040. Trying again.
14/06/09 00:04:12 INFO JettyUtils: Error was: Failure(java.net.BindException: Address already in use)
14/06/09 00:04:12 INFO Server: jetty-8.y.z-SNAPSHOT
14/06/09 00:04:12 INFO AbstractConnector: Started SelectChannelConnector@0.0.0.0:4041
14/06/09 00:04:12 INFO SparkUI: Started SparkUI at http://aash-mbp.local:4041
```

Lengthy logging comes from this line of code in Jetty: http://grepcode.com/file/repo1.maven.org/maven2/org.eclipse.jetty.aggregate/jetty-all/9.1.3.v20140225/org/eclipse/jetty/util/component/AbstractLifeCycle.java#210

Author: Andrew Ash <andrew@andrewash.com>

Closes #1019 from ash211/SPARK-1902 and squashes the following commits:

0dd02f7 [Andrew Ash] Leave old org.eclipse.jetty silencing in place
1e2866b [Andrew Ash] Address CR comments
9d85eed [Andrew Ash] SPARK-1902 Silence stacktrace from logs when doing port failover to port n+1
[SPARK-1970] Update unit test in XORShiftRandomSuite to use ChiSquareTest from commons-math3

Updating the chisquare unit test in XORShiftRandomSuite to use the ChiSquareTest in commons-math3 instead of hardcoding the chisquare statistic for the desired confidence interval.

Author: Doris Xin <doris.s.xin@gmail.com>

Closes #1073 from dorx/math3Unit and squashes the following commits:

da0e891 [Doris Xin] remove math3 from common pom
9954143 [Doris Xin] merge master
c19948f [Doris Xin] Merge branch 'master' into math3Unit
8f84f19 [Doris Xin] [SPARK-1970] unit test in XORShiftRandomSuite
ffea61a [Doris Xin] SPARK-1939: Refactor takeSample method in RDD
1441977 [Doris Xin] SPARK-1939 Refactor takeSample method in RDD to use ScaSRS
HOTFIX: Fixing style error introduced by 08d0ac
[SPARK-2061] Made splits deprecated in JavaRDDLike

The jira for the issue can be found at: https://issues.apache.org/jira/browse/SPARK-2061
Most of spark has used over to consistently using `partitions` instead of `splits`. We should do likewise and add a `partitions` method to JavaRDDLike and have `splits` just call that. We should also go through all cases where other API's (e.g. Python) call `splits` and we should change those to use the newer API.

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

Closes #1062 from anantasty/SPARK-2061 and squashes the following commits:

b83ce6b [Anant] Fixed syntax issue
21f9210 [Anant] Fixed version number in deprecation string
9315b76 [Anant] made related changes to use partitions in python api
8c62dd1 [Anant] Made splits deprecated in JavaRDDLike
Fix some tests.

- JavaAPISuite was trying to compare a bare path with a URI. Fix by
  extracting the path from the URI, since we know it should be a
  local path anyway/

- b9be1609 excluded the ASM dependency everywhere, but easymock needs
  it (because cglib needs it). So re-add the dependency, with test
  scope this time.

The second one above actually uncovered a weird situation: the maven
test target works, even though I can't find the class sbt complains
about in its classpath. sbt complains with:

  [error] Uncaught exception when running org.apache.spark.util
  .random.RandomSamplerSuite: java.lang.NoClassDefFoundError:
  org/objectweb/asm/Type

To avoid more weirdness caused by that, I explicitly added the asm
dependency to both maven and sbt (for tests only), and verified
the classes don't end up in the final assembly.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #917 from vanzin/flaky-tests and squashes the following commits:

d022320 [Marcelo Vanzin] Fix some tests.
[SQL] Pass SQLContext instead of SparkContext into physical operators.

This makes it easier to use config options in operators.

Author: Reynold Xin <rxin@apache.org>

Closes #1164 from rxin/sqlcontext and squashes the following commits:

797b2fd [Reynold Xin] Pass SQLContext instead of SparkContext into physical operators.
[SQL] Break hiveOperators.scala into multiple files.

The single file was getting very long (500+ loc).

Author: Reynold Xin <rxin@apache.org>

Closes #1166 from rxin/hiveOperators and squashes the following commits:

5b43068 [Reynold Xin] [SQL] Break hiveOperators.scala into multiple files.
HOTFIX: Fix missing MIMA ignore
HOTFIX: Add excludes for new MIMA files
SPARK-1996. Remove use of special Maven repo for Akka

Just following up Matei's suggestion to remove the Akka repo references. Builds and the audit-release script appear OK.

Author: Sean Owen <sowen@cloudera.com>

Closes #1170 from srowen/SPARK-1996 and squashes the following commits:

5ca2930 [Sean Owen] Remove outdated Akka repository references
SPARK-2231: dev/run-tests should include YARN and use a recent Hadoop version

...rsion

Author: Patrick Wendell <pwendell@gmail.com>

Closes #1175 from pwendell/test-hadoop-version and squashes the following commits:

9210ef4 [Patrick Wendell] SPARK-2231: dev/run-tests should include YARN and use a recent Hadoop version
SPARK-2034. KafkaInputDStream doesn't close resources and may prevent JVM shutdown

Tobias noted today on the mailing list:

========

I am trying to use Spark Streaming with Kafka, which works like a
charm – except for shutdown. When I run my program with "sbt
run-main", sbt will never exit, because there are two non-daemon
threads left that don't die.
I created a minimal example at
<https://gist.github.com/tgpfeiffer/b1e765064e983449c6b6#file-kafkadoesntshutdown-scala>.
It starts a StreamingContext and does nothing more than connecting to
a Kafka server and printing what it receives. Using the `future
Unknown macro: { ... }
` construct, I shut down the StreamingContext after some seconds and
then print the difference between the threads at start time and at end
time. The output can be found at
<https://gist.github.com/tgpfeiffer/b1e765064e983449c6b6#file-output1>.
There are a number of threads remaining that will prevent sbt from
exiting.
When I replace `KafkaUtils.createStream(...)` with a call that does
exactly the same, except that it calls `consumerConnector.shutdown()`
in `KafkaReceiver.onStop()` (which it should, IMO), the output is as
shown at <https://gist.github.com/tgpfeiffer/b1e765064e983449c6b6#file-output2>.
Does anyone have any idea what is going on here and why the program
doesn't shut down properly? The behavior is the same with both kafka
0.8.0 and 0.8.1.1, by the way.

========

Something similar was noted last year:

http://mail-archives.apache.org/mod_mbox/spark-dev/201309.mbox/%3C1380220041.2428.YahooMailNeo@web160804.mail.bf1.yahoo.com%3E

KafkaInputDStream doesn't close `ConsumerConnector` in `onStop()`, and does not close the `Executor` it creates. The latter leaves non-daemon threads and can prevent the JVM from shutting down even if streaming is closed properly.

Author: Sean Owen <sowen@cloudera.com>

Closes #980 from srowen/SPARK-2034 and squashes the following commits:

9f31a8d [Sean Owen] Restore ClassTag to private class because MIMA flags it; is the shadowing intended?
2d579a8 [Sean Owen] Close ConsumerConnector in onStop; shutdown() the local Executor that is created so that its threads stop when done; close the Zookeeper client even on exception; fix a few typos; log exceptions that otherwise vanish