SPARK-1431: Allow merging conflicting pull requests

Sometimes if there is a small conflict it's nice to be able to just
manually fix it up rather than have another RTT with the contributor.

Author: Patrick Wendell <pwendell@gmail.com>

Closes #342 from pwendell/merge-conflicts and squashes the following commits:

cdce61a [Patrick Wendell] SPARK-1431: Allow merging conflicting pull requests
[SQL] SPARK-1371 Hash Aggregation Improvements

Given:
```scala
case class Data(a: Int, b: Int)
val rdd =
  sparkContext
    .parallelize(1 to 200)
    .flatMap(_ => (1 to 50000).map(i => Data(i % 100, i)))
rdd.registerAsTable("data")
cacheTable("data")
```
Before:
```
SELECT COUNT(*) FROM data:[10000000]
16795.567ms
SELECT a, SUM(b) FROM data GROUP BY a
7536.436ms
SELECT SUM(b) FROM data
10954.1ms
```

After:
```
SELECT COUNT(*) FROM data:[10000000]
1372.175ms
SELECT a, SUM(b) FROM data GROUP BY a
2070.446ms
SELECT SUM(b) FROM data
958.969ms
```

Author: Michael Armbrust <michael@databricks.com>

Closes #295 from marmbrus/hashAgg and squashes the following commits:

ec63575 [Michael Armbrust] Add comment.
d0495a9 [Michael Armbrust] Use scaladoc instead.
b4a6887 [Michael Armbrust] Address review comments.
a2d90ba [Michael Armbrust] Capture child output statically to avoid issues with generators and serialization.
7c13112 [Michael Armbrust] Rewrite Aggregate operator to stream input and use projections.  Remove unused local RDD functions implicits.
5096f99 [Michael Armbrust] Make HiveUDAF fields transient since object inspectors are not serializable.
6a4b671 [Michael Armbrust] Add option to avoid binding operators expressions automatically.
92cca08 [Michael Armbrust] Always include serialization debug info when running tests.
1279df2 [Michael Armbrust] Increase default number of partitions.
[SQL] SPARK-1427 Fix toString for SchemaRDD NativeCommands.

Author: Michael Armbrust <michael@databricks.com>

Closes #343 from marmbrus/toStringFix and squashes the following commits:

37198fe [Michael Armbrust] Fix toString for SchemaRDD NativeCommands.
SPARK-1432: Make sure that all metadata fields are properly cleaned

While working on spark-1337 with @pwendell, we noticed that not all of the metadata maps in JobProgessListener were being properly cleaned. This could lead to a (hypothetical) memory leak issue should a job run long enough. This patch aims to address the issue.

Author: Davis Shepherd <davis@conviva.com>

Closes #338 from dgshep/master and squashes the following commits:

a77b65c [Davis Shepherd] In the contex of SPARK-1337: Make sure that all metadata fields are properly cleaned
[sql] Rename Expression.apply to eval for better readability.

Also used this opportunity to add a bunch of override's and made some members private.

Author: Reynold Xin <rxin@apache.org>

Closes #340 from rxin/eval and squashes the following commits:

a7c7ca7 [Reynold Xin] Fixed conflicts in merge.
9069de6 [Reynold Xin] Merge branch 'master' into eval
3ccc313 [Reynold Xin] Merge branch 'master' into eval
1a47e10 [Reynold Xin] Renamed apply to eval for generators and added a bunch of override's.
ea061de [Reynold Xin] Rename Expression.apply to eval for better readability.
SPARK-1252. On YARN, use container-log4j.properties for executors

container-log4j.properties is a file that YARN provides so that containers can have log4j.properties distinct from that of the NodeManagers.

Logs now go to syslog, and stderr and stdout just have the process's standard err and standard out.

I tested this on pseudo-distributed clusters for both yarn (Hadoop 2.2) and yarn-alpha (Hadoop 0.23.7)/

Author: Sandy Ryza <sandy@cloudera.com>

Closes #148 from sryza/sandy-spark-1252 and squashes the following commits:

c0043b8 [Sandy Ryza] Put log4j.properties file under common
55823da [Sandy Ryza] Add license headers to new files
10934b8 [Sandy Ryza] Add log4j-spark-container.properties and support SPARK_LOG4J_CONF
e74450b [Sandy Ryza] SPARK-1252. On YARN, use container-log4j.properties for executors
HOTFIX: Disable actor input stream test.

This test makes incorrect assumptions about the behavior of Thread.sleep().

Author: Patrick Wendell <pwendell@gmail.com>

Closes #347 from pwendell/stream-tests and squashes the following commits:

10e09e0 [Patrick Wendell] HOTFIX: Disable actor input stream.
SPARK-1099: Introduce local[*] mode to infer number of cores

This is the default mode for running spark-shell and pyspark, intended to allow users running spark for the first time to see the performance benefits of using multiple cores, while not breaking backwards compatibility for users who use "local" mode and expect exactly 1 core.

Author: Aaron Davidson <aaron@databricks.com>

Closes #182 from aarondav/110 and squashes the following commits:

a88294c [Aaron Davidson] Rebased changes for new spark-shell
a9f393e [Aaron Davidson] SPARK-1099: Introduce local[*] mode to infer number of cores
[sql] Rename execution/aggregates.scala Aggregate.scala, and added a bunch of private[this] to variables.

Author: Reynold Xin <rxin@apache.org>

Closes #348 from rxin/aggregate and squashes the following commits:

f4bc36f [Reynold Xin] Rename execution/aggregates.scala Aggregate.scala, and added a bunch of private[this] to variables.
Removed the default eval implementation from Expression, and added a bunch of override's in classes I touched.

It is more robust to not provide a default implementation for Expression's.

Author: Reynold Xin <rxin@apache.org>

Closes #350 from rxin/eval-default and squashes the following commits:

0a83b8f [Reynold Xin] Removed the default eval implementation from Expression, and added a bunch of override's in classes I touched.
Added eval for Rand (without any support for user-defined seed).

Author: Reynold Xin <rxin@apache.org>

Closes #349 from rxin/rand and squashes the following commits:

fd11322 [Reynold Xin] Added eval for Rand (without any support for user-defined seed).
Change timestamp cast semantics. When cast to numeric types, return the unix time in seconds (instead of millis).

@marmbrus @chenghao-intel

Author: Reynold Xin <rxin@apache.org>

Closes #352 from rxin/timestamp-cast and squashes the following commits:

18aacd3 [Reynold Xin] Fixed precision for double.
2adb235 [Reynold Xin] Change timestamp cast semantics. When cast to numeric types, return the unix time in seconds (instead of millis).
[SPARK-1402]  Added 3 more compression schemes

JIRA issue: [SPARK-1402](https://issues.apache.org/jira/browse/SPARK-1402)

This PR provides 3 more compression schemes for Spark SQL in-memory columnar storage:

* `BooleanBitSet`
* `IntDelta`
* `LongDelta`

Now there are 6 compression schemes in total, including the no-op `PassThrough` scheme.

Also fixed a bug in PR #286: not all compression schemes are added as available schemes when accessing an in-memory column, and when a column is compressed with an unrecognised scheme, `ColumnAccessor` throws exception.

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

Closes #330 from liancheng/moreCompressionSchemes and squashes the following commits:

1d037b8 [Cheng Lian] Fixed SPARK-1436: in-memory column byte buffer must be able to be accessed multiple times
d7c0e8f [Cheng Lian] Added test suite for IntegralDelta (IntDelta & LongDelta)
3c1ad7a [Cheng Lian] Added test suite for BooleanBitSet, refactored other test suites
44fe4b2 [Cheng Lian] Refactored CompressionScheme, added 3 more compression schemes.
[SPARK-1103] Automatic garbage collection of RDD, shuffle and broadcast data

This PR allows Spark to automatically cleanup metadata and data related to persisted RDDs, shuffles and broadcast variables when the corresponding RDDs, shuffles and broadcast variables fall out of scope from the driver program. This is still a work in progress as broadcast cleanup has not been implemented.

**Implementation Details**
A new class `ContextCleaner` is responsible cleaning all the state. It is instantiated as part of a `SparkContext`. RDD and ShuffleDependency classes have overridden `finalize()` function that gets called whenever their instances go out of scope. The `finalize()` function enqueues the object’s identifier (i.e. RDD ID, shuffle ID, etc.) with the `ContextCleaner`, which is a very short and cheap operation and should not significantly affect the garbage collection mechanism. The `ContextCleaner`, on a different thread, performs the cleanup, whose details are given below.

*RDD cleanup:*
`ContextCleaner` calls `RDD.unpersist()` is used to cleanup persisted RDDs. Regarding metadata, the DAGScheduler automatically cleans up all metadata related to a RDD after all jobs have completed. Only the `SparkContext.persistentRDDs` keeps strong references to persisted RDDs. The `TimeStampedHashMap` used for that has been replaced by `TimeStampedWeakValueHashMap` that keeps only weak references to the RDDs, allowing them to be garbage collected.

*Shuffle cleanup:*
New BlockManager message `RemoveShuffle(<shuffle ID>)` asks the `BlockManagerMaster` and currently active `BlockManager`s to delete all the disk blocks related to the shuffle ID. `ContextCleaner` cleans up shuffle data using this message and also cleans up the metadata in the `MapOutputTracker` of the driver. The `MapOutputTracker` at the workers, that caches the shuffle metadata, maintains a `BoundedHashMap` to limit the shuffle information it caches. Refetching the shuffle information from the driver is not too costly.

*Broadcast cleanup:*
To be done. [This PR](https://github.com/apache/incubator-spark/pull/543/) adds mechanism for explicit cleanup of broadcast variables. `Broadcast.finalize()` will enqueue its own ID with ContextCleaner and the PRs mechanism will be used to unpersist the Broadcast data.

*Other cleanup:*
`ShuffleMapTask` and `ResultTask` caches tasks and used TTL based cleanup (using `TimeStampedHashMap`), so nothing got cleaned up if TTL was not set. Instead, they now use `BoundedHashMap` to keep a limited number of map output information. Cost of repopulating the cache if necessary is very small.

**Current state of implementation**
Implemented RDD and shuffle cleanup. Things left to be done are.
- Cleaning up for broadcast variable still to be done.
- Automatic cleaning up keys with empty weak refs as values in `TimeStampedWeakValueHashMap`

Author: Tathagata Das <tathagata.das1565@gmail.com>
Author: Andrew Or <andrewor14@gmail.com>
Author: Roman Pastukhov <ignatich@mail.ru>

Closes #126 from tdas/state-cleanup and squashes the following commits:

61b8d6e [Tathagata Das] Fixed issue with Tachyon + new BlockManager methods.
f489fdc [Tathagata Das] Merge remote-tracking branch 'apache/master' into state-cleanup
d25a86e [Tathagata Das] Fixed stupid typo.
cff023c [Tathagata Das] Fixed issues based on Andrew's comments.
4d05314 [Tathagata Das] Scala style fix.
2b95b5e [Tathagata Das] Added more documentation on Broadcast implementations, specially which blocks are told about to the driver. Also, fixed Broadcast API to hide destroy functionality.
41c9ece [Tathagata Das] Added more unit tests for BlockManager, DiskBlockManager, and ContextCleaner.
6222697 [Tathagata Das] Fixed bug and adding unit test for removeBroadcast in BlockManagerSuite.
104a89a [Tathagata Das] Fixed failing BroadcastSuite unit tests by introducing blocking for removeShuffle and removeBroadcast in BlockManager*
a430f06 [Tathagata Das] Fixed compilation errors.
b27f8e8 [Tathagata Das] Merge pull request #3 from andrewor14/cleanup
cd72d19 [Andrew Or] Make automatic cleanup configurable (not documented)
ada45f0 [Andrew Or] Merge branch 'state-cleanup' of github.com:tdas/spark into cleanup
a2cc8bc [Tathagata Das] Merge remote-tracking branch 'apache/master' into state-cleanup
c5b1d98 [Andrew Or] Address Patrick's comments
a6460d4 [Andrew Or] Merge github.com:apache/spark into cleanup
762a4d8 [Tathagata Das] Merge pull request #1 from andrewor14/cleanup
f0aabb1 [Andrew Or] Correct semantics for TimeStampedWeakValueHashMap + add tests
5016375 [Andrew Or] Address TD's comments
7ed72fb [Andrew Or] Fix style test fail + remove verbose test message regarding broadcast
634a097 [Andrew Or] Merge branch 'state-cleanup' of github.com:tdas/spark into cleanup
7edbc98 [Tathagata Das] Merge remote-tracking branch 'apache-github/master' into state-cleanup
8557c12 [Andrew Or] Merge github.com:apache/spark into cleanup
e442246 [Andrew Or] Merge github.com:apache/spark into cleanup
88904a3 [Andrew Or] Make TimeStampedWeakValueHashMap a wrapper of TimeStampedHashMap
fbfeec8 [Andrew Or] Add functionality to query executors for their local BlockStatuses
34f436f [Andrew Or] Generalize BroadcastBlockId to remove BroadcastHelperBlockId
0d17060 [Andrew Or] Import, comments, and style fixes (minor)
c92e4d9 [Andrew Or] Merge github.com:apache/spark into cleanup
f201a8d [Andrew Or] Test broadcast cleanup in ContextCleanerSuite + remove BoundedHashMap
e95479c [Andrew Or] Add tests for unpersisting broadcast
544ac86 [Andrew Or] Clean up broadcast blocks through BlockManager*
d0edef3 [Andrew Or] Add framework for broadcast cleanup
ba52e00 [Andrew Or] Refactor broadcast classes
c7ccef1 [Andrew Or] Merge branch 'bc-unpersist-merge' of github.com:ignatich/incubator-spark into cleanup
6c9dcf6 [Tathagata Das] Added missing Apache license
d2f8b97 [Tathagata Das] Removed duplicate unpersistRDD.
a007307 [Tathagata Das] Merge remote-tracking branch 'apache/master' into state-cleanup
620eca3 [Tathagata Das] Changes based on PR comments.
f2881fd [Tathagata Das] Changed ContextCleaner to use ReferenceQueue instead of finalizer
e1fba5f [Tathagata Das] Style fix
892b952 [Tathagata Das] Removed use of BoundedHashMap, and made BlockManagerSlaveActor cleanup shuffle metadata in MapOutputTrackerWorker.
a7260d3 [Tathagata Das] Added try-catch in context cleaner and null value cleaning in TimeStampedWeakValueHashMap.
e61daa0 [Tathagata Das] Modifications based on the comments on PR 126.
ae9da88 [Tathagata Das] Removed unncessary TimeStampedHashMap from DAGScheduler, added try-catches in finalize() methods, and replaced ArrayBlockingQueue to LinkedBlockingQueue to avoid blocking in Java's finalizing thread.
cb0a5a6 [Tathagata Das] Fixed docs and styles.
a24fefc [Tathagata Das] Merge remote-tracking branch 'apache/master' into state-cleanup
8512612 [Tathagata Das] Changed TimeStampedHashMap to use WrappedJavaHashMap.
e427a9e [Tathagata Das] Added ContextCleaner to automatically clean RDDs and shuffles when they fall out of scope. Also replaced TimeStampedHashMap to BoundedHashMaps and TimeStampedWeakValueHashMap for the necessary hashmap behavior.
80dd977 [Roman Pastukhov] Fix for Broadcast unpersist patch.
1e752f1 [Roman Pastukhov] Added unpersist method to Broadcast.
[SPARK-1331] Added graceful shutdown to Spark Streaming

Current version of StreamingContext.stop() directly kills all the data receivers (NetworkReceiver) without waiting for the data already received to be persisted and processed. This PR provides the fix. Now, when the StreamingContext.stop() is called, the following sequence of steps will happen.
1. The driver will send a stop signal to all the active receivers.
2. Each receiver, when it gets a stop signal from the driver, first stop receiving more data, then waits for the thread that persists data blocks to BlockManager to finish persisting all receive data, and finally quits.
3. After all the receivers have stopped, the driver will wait for the Job Generator and Job Scheduler to finish processing all the received data.

It also fixes the semantics of StreamingContext.start and stop. It will throw appropriate errors and warnings if stop() is called before start(), stop() is called twice, etc.

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #247 from tdas/graceful-shutdown and squashes the following commits:

61c0016 [Tathagata Das] Updated MIMA binary check excludes.
ae1d39b [Tathagata Das] Merge remote-tracking branch 'apache-github/master' into graceful-shutdown
6b59cfc [Tathagata Das] Minor changes based on Andrew's comment on PR.
d0b8d65 [Tathagata Das] Reduced time taken by graceful shutdown unit test.
f55bc67 [Tathagata Das] Fix scalastyle
c69b3a7 [Tathagata Das] Updates based on Patrick's comments.
c43b8ae [Tathagata Das] Added graceful shutdown to Spark Streaming.
[SPARK-1396] Properly cleanup DAGScheduler on job cancellation.

Previously, when jobs were cancelled, not all of the state in the
DAGScheduler was cleaned up, leading to a slow memory leak in the
DAGScheduler.  As we expose easier ways to cancel jobs, it's more
important to fix these issues.

This commit also fixes a second and less serious problem, which is that
previously, when a stage failed, not all of the appropriate stages
were cancelled.  See the "failure of stage used by two jobs" test
for an example of this.  This just meant that extra work was done, and is
not a correctness problem.

This commit adds 3 tests.  “run shuffle with map stage failure” is
a new test to more thoroughly test this functionality, and passes on
both the old and new versions of the code.  “trivial job
cancellation” fails on the old code because all state wasn’t cleaned
up correctly when jobs were cancelled (we didn’t remove the job from
resultStageToJob).  “failure of stage used by two jobs” fails on the
old code because taskScheduler.cancelTasks wasn’t called for one of
the stages (see test comments).

This should be checked in before #246, which makes it easier to
cancel stages / jobs.

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #305 from kayousterhout/incremental_abort_fix and squashes the following commits:

f33d844 [Kay Ousterhout] Mark review comments
9217080 [Kay Ousterhout] Properly cleanup DAGScheduler on job cancellation.
Remove extra semicolon in import statement and unused import in ApplicationMaster

Small nit cleanup to remove extra semicolon and unused import in Yarn's stable ApplicationMaster (it bothers me every time I saw it)

Author: Henry Saputra <hsaputra@apache.org>

Closes #358 from hsaputra/nitcleanup_removesemicolon_import_applicationmaster and squashes the following commits:

bffb685 [Henry Saputra] Remove extra semicolon in import statement and unused import in ApplicationMaster.scala
SPARK-1348 binding Master, Worker, and App Web UI to all interfaces

Author: Kan Zhang <kzhang@apache.org>

Closes #318 from kanzhang/SPARK-1348 and squashes the following commits:

e625a5f [Kan Zhang] reverting the changes to startJettyServer()
7a8084e [Kan Zhang] SPARK-1348 binding Master, Worker, and App Web UI to all interfaces
SPARK-1445: compute-classpath should not print error if lib_managed not found

This was added to the check for the assembly jar, forgot it for the datanucleus jars.

Author: Aaron Davidson <aaron@databricks.com>

Closes #361 from aarondav/cc and squashes the following commits:

8facc16 [Aaron Davidson] SPARK-1445: compute-classpath should not print error if lib_managed not found
[SPARK-1397] Notify SparkListeners when stages fail or are cancelled.

[I wanted to post this for folks to comment but it depends on (and thus includes the changes in) a currently outstanding PR, #305.  You can look at just the second commit: https://github.com/kayousterhout/spark-1/commit/93f08baf731b9eaf5c9792a5373560526e2bccac to see just the changes relevant to this PR]

Previously, when stages fail or get cancelled, the SparkListener is only notified
indirectly through the SparkListenerJobEnd, where we sometimes pass in a single
stage that failed.  This worked before job cancellation, because jobs would only fail
due to a single stage failure.  However, with job cancellation, multiple running stages
can fail when a job gets cancelled.  Right now, this is not handled correctly, which
results in stages that get stuck in the “Running Stages” window in the UI even
though they’re dead.

This PR changes the SparkListenerStageCompleted event to a SparkListenerStageEnded
event, and uses this event to tell SparkListeners when stages fail in addition to when
they complete successfully.  This change is NOT publicly backward compatible for two
reasons.  First, it changes the SparkListener interface.  We could alternately add a new event,
SparkListenerStageFailed, and keep the existing SparkListenerStageCompleted.  However,
this is less consistent with the listener events for tasks / jobs ending, and will result in some
code duplication for listeners (because failed and completed stages are handled in similar
ways).  Note that I haven’t finished updating the JSON code to correctly handle the new event
because I’m waiting for feedback on whether this is a good or bad idea (hence the “WIP”).

It is also not backwards compatible because it changes the publicly visible JobWaiter.jobFailed()
method to no longer include a stage that caused the failure.  I think this change should definitely
stay, because with cancellation (as described above), a failure isn’t necessarily caused by a
single stage.

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #309 from kayousterhout/stage_cancellation and squashes the following commits:

5533ecd [Kay Ousterhout] Fixes in response to Mark's review
320c7c7 [Kay Ousterhout] Notify SparkListeners when stages fail or are cancelled.