This PR adds a new method `withWatermark` to the `Dataset` API, which can be used specify an _event time watermark_.  An event time watermark allows the streaming engine to reason about the point in time after which we no longer expect to see late data.  This PR also has augmented `StreamExecution` to use this watermark for several purposes:
  - To know when a given time window aggregation is finalized and thus results can be emitted when using output modes that do not allow updates (e.g. `Append` mode).
  - To minimize the amount of state that we need to keep for on-going aggregations, by evicting state for groups that are no longer expected to change.  Although, we do still maintain all state if the query requires (i.e. if the event time is not present in the `groupBy` or when running in `Complete` mode).

An example that emits windowed counts of records, waiting up to 5 minutes for late data to arrive.
```scala
df.withWatermark("eventTime", "5 minutes")
  .groupBy(window($"eventTime", "1 minute") as 'window)
  .count()
  .writeStream
  .format("console")
  .mode("append") // In append mode, we only output finalized aggregations.
  .start()
```

### Calculating the watermark.
The current event time is computed by looking at the `MAX(eventTime)` seen this epoch across all of the partitions in the query minus some user defined _delayThreshold_.  An additional constraint is that the watermark must increase monotonically.

Note that since we must coordinate this value across partitions occasionally, the actual watermark used is only guaranteed to be at least `delay` behind the actual event time.  In some cases we may still process records that arrive more than delay late.

This mechanism was chosen for the initial implementation over processing time for two reasons:
  - it is robust to downtime that could affect processing delay
  - it does not require syncing of time or timezones between the producer and the processing engine.

### Other notable implementation details
 - A new trigger metric `eventTimeWatermark` outputs the current value of the watermark.
 - We mark the event time column in the `Attribute` metadata using the key `spark.watermarkDelay`.  This allows downstream operations to know which column holds the event time.  Operations like `window` propagate this metadata.
 - `explain()` marks the watermark with a suffix of `-T${delayMs}` to ease debugging of how this information is propagated.
 - Currently, we don't filter out late records, but instead rely on the state store to avoid emitting records that are both added and filtered in the same epoch.

### Remaining in this PR
 - [ ] The test for recovery is currently failing as we don't record the watermark used in the offset log.  We will need to do so to ensure determinism, but this is deferred until #15626 is merged.

### Other follow-ups
There are some natural additional features that we should consider for future work:
 - Ability to write records that arrive too late to some external store in case any out-of-band remediation is required.
 - `Update` mode so you can get partial results before a group is evicted.
 - Other mechanisms for calculating the watermark.  In particular a watermark based on quantiles would be more robust to outliers.

Author: Michael Armbrust <michael@databricks.com>

Closes #15702 from marmbrus/watermarks.

(cherry picked from commit c0718782)
Signed-off-by: Tathagata Das <tathagata.das1565@gmail.com>

## What changes were proposed in this pull request?
This patch introduces three new annotations under InterfaceStability:
- Stable
- Evolving
- Unstable

This is inspired by Hadoop's InterfaceStability, and the first step towards switching over to a new API stability annotation framework.

## How was this patch tested?
N/A

Author: Reynold Xin <rxin@databricks.com>

Closes #15374 from rxin/SPARK-17800.

## What changes were proposed in this pull request?

Jira : https://issues.apache.org/jira/browse/SPARK-17495

Spark internally uses Murmur3Hash for partitioning. This is different from the one used by Hive. For queries which use bucketing this leads to different results if one tries the same query on both engines. For us, we want users to have backward compatibility to that one can switch parts of applications across the engines without observing regressions.

This PR includes `HiveHash`, `HiveHashFunction`, `HiveHasher` which mimics Hive's hashing at https://github.com/apache/hive/blob/master/serde/src/java/org/apache/hadoop/hive/serde2/objectinspector/ObjectInspectorUtils.java#L638

I am intentionally not introducing any usages of this hash function in rest of the code to keep this PR small. My eventual goal is to have Hive bucketing support in Spark. Once this PR gets in, I will make hash function pluggable in relevant areas (eg. `HashPartitioning`'s `partitionIdExpression` has Murmur3 hardcoded : https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/physical/partitioning.scala#L265)

## How was this patch tested?

Added `HiveHashSuite`

Author: Tejas Patil <tejasp@fb.com>

Closes #15047 from tejasapatil/SPARK-17495_hive_hash.

## What changes were proposed in this pull request?

Made changes to record length offsets to make them uniform throughout various areas of Spark core and unsafe

## How was this patch tested?

This change affects only SPARC architectures and was tested on X86 architectures as well for regression.

Author: sumansomasundar <suman.somasundar@oracle.com>

Closes #14762 from sumansomasundar/master.

## What changes were proposed in this pull request?

This PR introduces more compact representation for ```UnsafeArrayData```.

```UnsafeArrayData``` needs to accept ```null``` value in each entry of an array. In the current version, it has three parts
```
[numElements] [offsets] [values]
```
`Offsets` has the number of `numElements`, and represents `null` if its value is negative. It may increase memory footprint, and introduces an indirection for accessing each of `values`.

This PR uses bitvectors to represent nullability for each element like `UnsafeRow`, and eliminates an indirection for accessing each element. The new ```UnsafeArrayData``` has four parts.
```
[numElements][null bits][values or offset&length][variable length portion]
```
In the `null bits` region, we store 1 bit per element, represents whether an element is null. Its total size is ceil(numElements / 8) bytes, and it is aligned to 8-byte boundaries.
In the `values or offset&length` region, we store the content of elements. For fields that hold fixed-length primitive types, such as long, double, or int, we store the value directly in the field. For fields with non-primitive or variable-length values, we store a relative offset (w.r.t. the base address of the array) that points to the beginning of the variable-length field and length (they are combined into a long). Each is word-aligned. For `variable length portion`, each is aligned to 8-byte boundaries.

The new format can reduce memory footprint and improve performance of accessing each element. An example of memory foot comparison:
1024x1024 elements integer array
Size of ```baseObject``` for ```UnsafeArrayData```: 8 + 1024x1024 + 1024x1024 = 2M bytes
Size of ```baseObject``` for ```UnsafeArrayData```: 8 + 1024x1024/8 + 1024x1024 = 1.25M bytes

In summary, we got 1.0-2.6x performance improvements over the code before applying this PR.
Here are performance results of [benchmark programs](https://github.com/kiszk/spark/blob/04d2e4b6dbdc4eff43ce18b3c9b776e0129257c7/sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/UnsafeArrayDataBenchmark.scala):

**Read UnsafeArrayData**: 1.7x and 1.6x performance improvements over the code before applying this PR
````
OpenJDK 64-Bit Server VM 1.8.0_91-b14 on Linux 4.4.11-200.fc22.x86_64
Intel Xeon E3-12xx v2 (Ivy Bridge)

Without SPARK-15962
Read UnsafeArrayData:                    Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
Int                                            430 /  436        390.0           2.6       1.0X
Double                                         456 /  485        367.8           2.7       0.9X

With SPARK-15962
Read UnsafeArrayData:                    Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
Int                                            252 /  260        666.1           1.5       1.0X
Double                                         281 /  292        597.7           1.7       0.9X
````
**Write UnsafeArrayData**: 1.0x and 1.1x performance improvements over the code before applying this PR
````
OpenJDK 64-Bit Server VM 1.8.0_91-b14 on Linux 4.0.4-301.fc22.x86_64
Intel Xeon E3-12xx v2 (Ivy Bridge)

Without SPARK-15962
Write UnsafeArrayData:                   Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
Int                                            203 /  273        103.4           9.7       1.0X
Double                                         239 /  356         87.9          11.4       0.8X

With SPARK-15962
Write UnsafeArrayData:                   Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
Int                                            196 /  249        107.0           9.3       1.0X
Double                                         227 /  367         92.3          10.8       0.9X
````

**Get primitive array from UnsafeArrayData**: 2.6x and 1.6x performance improvements over the code before applying this PR
````
OpenJDK 64-Bit Server VM 1.8.0_91-b14 on Linux 4.0.4-301.fc22.x86_64
Intel Xeon E3-12xx v2 (Ivy Bridge)

Without SPARK-15962
Get primitive array from UnsafeArrayData: Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
Int                                            207 /  217        304.2           3.3       1.0X
Double                                         257 /  363        245.2           4.1       0.8X

With SPARK-15962
Get primitive array from UnsafeArrayData: Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
Int                                            151 /  198        415.8           2.4       1.0X
Double                                         214 /  394        293.6           3.4       0.7X
````

**Create UnsafeArrayData from primitive array**: 1.7x and 2.1x performance improvements over the code before applying this PR
````
OpenJDK 64-Bit Server VM 1.8.0_91-b14 on Linux 4.0.4-301.fc22.x86_64
Intel Xeon E3-12xx v2 (Ivy Bridge)

Without SPARK-15962
Create UnsafeArrayData from primitive array: Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
Int                                            340 /  385        185.1           5.4       1.0X
Double                                         479 /  705        131.3           7.6       0.7X

With SPARK-15962
Create UnsafeArrayData from primitive array: Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
Int                                            206 /  211        306.0           3.3       1.0X
Double                                         232 /  406        271.6           3.7       0.9X
````

1.7x and 1.4x performance improvements in [```UDTSerializationBenchmark```](https://github.com/apache/spark/blob/master/mllib/src/test/scala/org/apache/spark/mllib/linalg/UDTSerializationBenchmark.scala)  over the code before applying this PR
````
OpenJDK 64-Bit Server VM 1.8.0_91-b14 on Linux 4.4.11-200.fc22.x86_64
Intel Xeon E3-12xx v2 (Ivy Bridge)

Without SPARK-15962
VectorUDT de/serialization:              Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
serialize                                      442 /  533          0.0      441927.1       1.0X
deserialize                                    217 /  274          0.0      217087.6       2.0X

With SPARK-15962
VectorUDT de/serialization:              Best/Avg Time(ms)    Rate(M/s)   Per Row(ns)   Relative
------------------------------------------------------------------------------------------------
serialize                                      265 /  318          0.0      265138.5       1.0X
deserialize                                    155 /  197          0.0      154611.4       1.7X
````

## How was this patch tested?

Added unit tests into ```UnsafeArraySuite```

Author: Kazuaki Ishizaki <ishizaki@jp.ibm.com>

Closes #13680 from kiszk/SPARK-15962.

## What changes were proposed in this pull request?
This PR is to fix the code style errors before 2.0.1 release.

## How was this patch tested?
Manual.

Before:
```
./dev/lint-java
Using `mvn` from path: /usr/local/bin/mvn
Checkstyle checks failed at following occurrences:
[ERROR] src/main/java/org/apache/spark/network/client/TransportClient.java:[153] (sizes) LineLength: Line is longer than 100 characters (found 107).
[ERROR] src/main/java/org/apache/spark/network/client/TransportClient.java:[196] (sizes) LineLength: Line is longer than 100 characters (found 108).
[ERROR] src/main/java/org/apache/spark/network/client/TransportClient.java:[239] (sizes) LineLength: Line is longer than 100 characters (found 115).
[ERROR] src/main/java/org/apache/spark/network/server/TransportRequestHandler.java:[119] (sizes) LineLength: Line is longer than 100 characters (found 107).
[ERROR] src/main/java/org/apache/spark/network/server/TransportRequestHandler.java:[129] (sizes) LineLength: Line is longer than 100 characters (found 104).
[ERROR] src/main/java/org/apache/spark/network/util/LevelDBProvider.java:[124,11] (modifier) ModifierOrder: 'static' modifier out of order with the JLS suggestions.
[ERROR] src/main/java/org/apache/spark/network/util/TransportConf.java:[26] (regexp) RegexpSingleline: No trailing whitespace allowed.
[ERROR] src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java:[33] (sizes) LineLength: Line is longer than 100 characters (found 110).
[ERROR] src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java:[38] (sizes) LineLength: Line is longer than 100 characters (found 110).
[ERROR] src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java:[43] (sizes) LineLength: Line is longer than 100 characters (found 106).
[ERROR] src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java:[48] (sizes) LineLength: Line is longer than 100 characters (found 110).
[ERROR] src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeInMemorySorter.java:[0] (misc) NewlineAtEndOfFile: File does not end with a newline.
[ERROR] src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeSorterSpillReader.java:[67] (sizes) LineLength: Line is longer than 100 characters (found 106).
[ERROR] src/main/java/org/apache/spark/network/yarn/YarnShuffleService.java:[200] (regexp) RegexpSingleline: No trailing whitespace allowed.
[ERROR] src/main/java/org/apache/spark/network/yarn/YarnShuffleService.java:[309] (regexp) RegexpSingleline: No trailing whitespace allowed.
[ERROR] src/main/java/org/apache/spark/network/yarn/YarnShuffleService.java:[332] (regexp) RegexpSingleline: No trailing whitespace allowed.
[ERROR] src/main/java/org/apache/spark/network/yarn/YarnShuffleService.java:[348] (regexp) RegexpSingleline: No trailing whitespace allowed.
 ```
After:
```
./dev/lint-java
Using `mvn` from path: /usr/local/bin/mvn
Checkstyle checks passed.
```

Author: Weiqing Yang <yangweiqing001@gmail.com>

Closes #15170 from Sherry302/fixjavastyle.

Currently, the code is just swallowing exceptions, and not really checking
whether the auth information was being recorded properly. Fix both problems,
and also avoid tests inadvertently affecting other tests by modifying the
shared config variable (by making it not shared).

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #15161 from vanzin/SPARK-17611.

## What changes were proposed in this pull request?

The Maven module `common/network-shuffle` does not have a log4j configuration file for its test cases. So, added `log4j.properties` in the directory `src/test/resources`.

…shuffle]

Author: Jagadeesan <as2@us.ibm.com>

Closes #15108 from jagadeesanas2/SPARK-17543.

## What changes were proposed in this pull request?
Upgrade netty-all to latest in the 4.0.x line which is 4.0.41, mentions several bug fixes and performance improvements we may find useful, see netty.io/news/2016/08/29/4-0-41-Final-4-1-5-Final.html. Initially tried to use 4.1.5 but noticed it's not backwards compatible.

## How was this patch tested?
Existing unit tests against branch-1.6 and branch-2.0 using IBM Java 8 on Intel, Power and Z architectures

Author: Adam Roberts <aroberts@uk.ibm.com>

Closes #14961 from a-roberts/netty.

The secrets leveldb isn't being moved if you run spark shuffle services without yarn nm recovery on and then turn it on.  This fixes that.  I unfortunately missed this when I ported the patch from our internal branch 2 to master branch due to the changes for the recovery path.  Note this only applies to master since it is the only place the yarn nm recovery dir is used.

Unit tests ran and tested on 8 node cluster.  Fresh startup with NM recovery, fresh startup no nm recovery, switching between no nm recovery and recovery.  Also tested running applications to make sure wasn't affected by rolling upgrade.

Author: Thomas Graves <tgraves@prevailsail.corp.gq1.yahoo.com>
Author: Tom Graves <tgraves@apache.org>

Closes #14999 from tgravescs/SPARK-17433.

## What changes were proposed in this pull request?
TRIM/LTRIM/RTRIM should not strips characters other than spaces, we were trimming all chars small than ASCII 0x20(space)

## How was this patch tested?
fixed existing tests.

Author: Sandeep Singh <sandeep@techaddict.me>

Closes #14924 from techaddict/SPARK-17299.

The Spark Yarn Shuffle Service doesn't re-initialize the application credentials early enough which causes any other spark executors trying to fetch from that node during a rolling upgrade to fail with "java.lang.NullPointerException: Password cannot be null if SASL is enabled".  Right now the spark shuffle service relies on the Yarn nodemanager to re-register the applications, unfortunately this is after we open the port for other executors to connect. If other executors connected before the re-register they get a null pointer exception which isn't a re-tryable exception and cause them to fail pretty quickly. To solve this I added another leveldb file so that it can save and re-initialize all the applications before opening the port for other executors to connect to it.  Adding another leveldb was simpler from the code structure point of view.

Most of the code changes are moving things to common util class.

Patch was tested manually on a Yarn cluster with rolling upgrade was happing while spark job was running. Without the patch I consistently get the NullPointerException, with the patch the job gets a few Connection refused exceptions but the retries kick in and the it succeeds.

Author: Thomas Graves <tgraves@staydecay.corp.gq1.yahoo.com>

Closes #14718 from tgravescs/SPARK-16711.

## What changes were proposed in this pull request?

Avoid allocating some 0-length arrays, esp. in UTF8String, and by using Array.empty in Scala over Array[T]()

## How was this patch tested?

Jenkins

Author: Sean Owen <sowen@cloudera.com>

Closes #14895 from srowen/SPARK-17331.

## What changes were proposed in this pull request?

Make all Java Loggers static members

## How was this patch tested?

Jenkins

Author: Sean Owen <sowen@cloudera.com>

Closes #14896 from srowen/SPARK-17332.

## What changes were proposed in this pull request?

When a thread is a Netty's FastThreadLocalThread, Netty will use its fast ThreadLocal implementation. It has a better performance than JDK's (See the benchmark results in https://github.com/netty/netty/pull/4417, note: it's not a fix to Netty's FastThreadLocal. It just fixed an issue in Netty's benchmark codes)

This PR just changed the ThreadFactory to Netty's DefaultThreadFactory which will use FastThreadLocalThread. There is also a minor change to the thread names. See https://github.com/netty/netty/blob/netty-4.0.22.Final/common/src/main/java/io/netty/util/concurrent/DefaultThreadFactory.java#L94

## How was this patch tested?

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #14879 from zsxwing/netty-thread.

[SPARK-17231][CORE] Avoid building debug or trace log messages unless the respective log level is enabled

(This PR addresses https://issues.apache.org/jira/browse/SPARK-17231)

## What changes were proposed in this pull request?

While debugging the performance of a large GraphX connected components computation, we found several places in the `network-common` and `network-shuffle` code bases where trace or debug log messages are constructed even if the respective log level is disabled. According to YourKit, these constructions were creating substantial churn in the eden region. Refactoring the respective code to avoid these unnecessary constructions except where necessary led to a modest but measurable reduction in our job's task time, GC time and the ratio thereof.

## How was this patch tested?

We computed the connected components of a graph with about 2.6 billion vertices and 1.7 billion edges four times. We used four different EC2 clusters each with 8 r3.8xl worker nodes. Two test runs used Spark master. Two used Spark master + this PR. The results from the first test run, master and master+PR:
![master](https://cloud.githubusercontent.com/assets/833693/17951634/7471cbca-6a18-11e6-9c26-78afe9319685.jpg)
![logging_perf_improvements](https://cloud.githubusercontent.com/assets/833693/17951632/7467844e-6a18-11e6-9a0e-053dc7650413.jpg)

The results from the second test run, master and master+PR:
![master 2](https://cloud.githubusercontent.com/assets/833693/17951633/746dd6aa-6a18-11e6-8e27-606680b3f105.jpg)
![logging_perf_improvements 2](https://cloud.githubusercontent.com/assets/833693/17951631/74488710-6a18-11e6-8a32-08692f373386.jpg)

Though modest, I believe these results are significant.

Author: Michael Allman <michael@videoamp.com>

Closes #14798 from mallman/spark-17231-logging_perf_improvements.

## # What changes were proposed in this pull request?

From the spark of version 2.0.0 , when MemoryMode.OFF_HEAP is set , whether the architecture supports unaligned access or not is checked. If the check doesn't pass, exception is raised.

We know that AArch64 also supports unaligned access , but now only i386, x86, amd64, and X86_64 are included.

I think we should include aarch64 when performing the check.

## How was this patch tested?

Unit test suite

Author: Richael <Richael.Zhuang@arm.com>

Closes #14700 from yimuxi/zym_change_unsafe.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #14499 from JoshRosen/hotfix.

## What changes were proposed in this pull request?

Shuffle fetch on large intermediate dataset is slow because the shuffle service open/close the index file for each shuffle fetch. This change introduces a cache for the index information so that we can avoid accessing the index files for each block fetch

## How was this patch tested?

Tested by running a job on the cluster and the shuffle read time was reduced by 50%.

Author: Sital Kedia <skedia@fb.com>

Closes #12944 from sitalkedia/shuffle_service.

[SPARK-16535][BUILD] In pom.xml, remove groupId which is redundant definition and inherited from the parent

https://issues.apache.org/jira/browse/SPARK-16535

## What changes were proposed in this pull request?

When I scan through the pom.xml of sub projects, I found this warning as below and attached screenshot
```
Definition of groupId is redundant, because it's inherited from the parent
```
![screen shot 2016-07-13 at 3 13 11 pm](https://cloud.githubusercontent.com/assets/3925641/16823121/744f893e-4916-11e6-8a52-042f83b9db4e.png)

I've tried to remove some of the lines with groupId definition, and the build on my local machine is still ok.
```
<groupId>org.apache.spark</groupId>
```
As I just find now `<maven.version>3.3.9</maven.version>` is being used in Spark 2.x, and Maven-3 supports versionless parent elements: Maven 3 will remove the need to specify the parent version in sub modules. THIS is great (in Maven 3.1).

ref: http://stackoverflow.com/questions/3157240/maven-3-worth-it/3166762#3166762

## How was this patch tested?

I've tested by re-building the project, and build succeeded.

Author: Xin Ren <iamshrek@126.com>

Closes #14189 from keypointt/SPARK-16535.

## What changes were proposed in this pull request?

This PR fixes four java linter `LineLength` errors. Those are all `LineLength` errors, but we had better remove all java linter errors before release.

## How was this patch tested?

After pass the Jenkins, `./dev/lint-java`.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #14255 from dongjoon-hyun/minor_java_linter.

This prevents the NM from starting when something is wrong, which would
lead to later errors which are confusing and harder to debug.

Added a unit test to verify startup fails if something is wrong.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #14162 from vanzin/SPARK-16505.

## What changes were proposed in this pull request?

Due to the changes of [SPARK-14963](https://issues.apache.org/jira/browse/SPARK-14963), external shuffle recovery file name is changed mistakenly, so here change it back to the previous file name.

This only affects the master branch, branch-2.0 is correct [here](https://github.com/apache/spark/blob/branch-2.0/common/network-yarn/src/main/java/org/apache/spark/network/yarn/YarnShuffleService.java#L195).

## How was this patch tested?

N/A

Author: jerryshao <sshao@hortonworks.com>

Closes #14197 from jerryshao/fix-typo-file-name.

## What changes were proposed in this pull request?

Fix Java style errors and remove unused imports, which are randomly found

## How was this patch tested?

Tested on my local machine.

Author: Xin Ren <iamshrek@126.com>

Closes #14161 from keypointt/SPARK-16437.

## What changes were proposed in this pull request?

Since externalShuffleService is essential for spark, better monitoring for shuffle service is necessary. In order to do so, we added various metrics in shuffle service and imported into ExternalShuffleServiceSource for metric system.
Metrics added in shuffle service:
* registeredExecutorsSize
* openBlockRequestLatencyMillis
* registerExecutorRequestLatencyMillis
* blockTransferRateBytes

JIRA Issue: https://issues.apache.org/jira/browse/SPARK-16405

## How was this patch tested?

Some test cases are added to verify metrics as expected in metric system. Those unit test cases are shown in `ExternalShuffleBlockHandlerSuite `

Author: Yangyang Liu <yangyangliu@fb.com>

Closes #14080 from lovexi/yangyang-metrics.

## What changes were proposed in this pull request?
After SPARK-16476 (committed earlier today as #14128), we can finally bump the version number.

## How was this patch tested?
N/A

Author: Reynold Xin <rxin@databricks.com>

Closes #14130 from rxin/SPARK-16477.

## What changes were proposed in this pull request?

This uses the try/finally pattern to ensure streams are closed after use. `UnsafeShuffleWriter` wasn't closing compression streams, causing them to leak resources until garbage collected. This was causing a problem with codecs that use off-heap memory.

## How was this patch tested?

Current tests are sufficient. This should not change behavior.

Author: Ryan Blue <blue@apache.org>

Closes #14093 from rdblue/SPARK-16420-unsafe-shuffle-writer-leak.

## What changes were proposed in this pull request?

This patches `MemoryAllocator` to fill clean and freed memory with known byte values, similar to https://github.com/jemalloc/jemalloc/wiki/Use-Case:-Find-a-memory-corruption-bug . Memory filling is flag-enabled in test only by default.

## How was this patch tested?

Unit test that it's on in test.

cc sameeragarwal

Author: Eric Liang <ekl@databricks.com>

Closes #13983 from ericl/spark-16021.

## What changes were proposed in this pull request?
Shade the netty.io namespace so that we can use it in shuffle independent of the dependencies being pulled by hadoop jars.

## How was this patch tested?
Ran a decent job involving shuffle write/read and tested the new spark-x-yarn-shuffle jar. After shading netty.io namespace, the nodemanager loads and shuffle job completes successfully.

Author: Dhruve Ashar <dhruveashar@gmail.com>

Closes #13739 from dhruve/bug/SPARK-16018.

## What changes were proposed in this pull request?

Currently, the memory for temporary buffer used by TimSort is always allocated as on-heap without bookkeeping, it could cause OOM both in on-heap and off-heap mode.

This PR will try to manage that by preallocate it together with the pointer array, same with RadixSort. It both works for on-heap and off-heap mode.

This PR also change the loadFactor of BytesToBytesMap to 0.5 (it was 0.70), it enables use to radix sort also makes sure that we have enough memory for timsort.

## How was this patch tested?

Existing tests.

Author: Davies Liu <davies@databricks.com>

Closes #13318 from davies/fix_timsort.

## What changes were proposed in this pull request?

This change resolves a number of build warnings that have accumulated, before 2.x. It does not address a large number of deprecation warnings, especially related to the Accumulator API. That will happen separately.

## How was this patch tested?

Jenkins

Author: Sean Owen <sowen@cloudera.com>

Closes #13377 from srowen/BuildWarnings.

## What changes were proposed in this pull request?

Remove call to Process.isAlive -- Java 8 only. Introduced in https://github.com/apache/spark/pull/13042 / SPARK-15263

## How was this patch tested?

Jenkins tests

Author: Sean Owen <sowen@cloudera.com>

Closes #13174 from srowen/SPARK-15386.

## What changes were proposed in this pull request?

Jira: https://issues.apache.org/jira/browse/SPARK-15263

The current logic for directory cleanup is slow because it does directory listing, recurses over child directories, checks for symbolic links, deletes leaf files and finally deletes the dirs when they are empty. There is back-and-forth switching from kernel space to user space while doing this. Since most of the deployment backends would be Unix systems, we could essentially just do `rm -rf` so that entire deletion logic runs in kernel space.

The current Java based impl in Spark seems to be similar to what standard libraries like guava and commons IO do (eg. http://svn.apache.org/viewvc/commons/proper/io/trunk/src/main/java/org/apache/commons/io/FileUtils.java?view=markup#l1540). However, guava removed this method in favour of shelling out to an operating system command (like in this PR). See the `Deprecated` note in older javadocs for guava for details : http://google.github.io/guava/releases/10.0.1/api/docs/com/google/common/io/Files.html#deleteRecursively(java.io.File)

Ideally, Java should be providing such APIs so that users won't have to do such things to get platform specific code. Also, its not just about speed, but also handling race conditions while doing at FS deletions is tricky. I could find this bug for Java in similar context : http://bugs.java.com/bugdatabase/view_bug.do?bug_id=7148952

## How was this patch tested?

I am relying on existing test cases to test the method. If there are suggestions about testing it, welcome to hear about it.

## Performance gains

*Input setup* : Created a nested directory structure of depth 3 and each entry having 50 sub-dirs. The input being cleaned up had total ~125k dirs.

Ran both approaches (in isolation) for 6 times to get average numbers:

Native Java cleanup  | `rm -rf` as a separate process
------------ | -------------
10.04 sec | 4.11 sec

This change made deletion 2.4 times faster for the given test input.

Author: Tejas Patil <tejasp@fb.com>

Closes #13042 from tejasapatil/delete_recursive.

## What changes were proposed in this pull request?

(See https://github.com/apache/spark/pull/12416 where most of this was already reviewed and committed; this is just the module structure and move part. This change does not move the annotations into test scope, which was the apparently problem last time.)

Rename `spark-test-tags` -> `spark-tags`; move common annotations like `Since` to `spark-tags`

## How was this patch tested?

Jenkins tests.

Author: Sean Owen <sowen@cloudera.com>

Closes #13074 from srowen/SPARK-15290.

## What changes were proposed in this pull request?

From Hadoop 2.5+, Yarn NM supports NM recovery which using recovery path for auxiliary services such as spark_shuffle, mapreduce_shuffle. So here change to use this path install of NM local dir if NM recovery is enabled.

## How was this patch tested?

Unit test + local test.

Author: jerryshao <sshao@hortonworks.com>

Closes #12994 from jerryshao/SPARK-14963.

## What changes were proposed in this pull request?
Remove LazyFileRegion instead use netty's DefaultFileRegion, since It was created so that we didn't create a file descriptor before having to send the file.

## How was this patch tested?
Existing tests

Author: Sandeep Singh <sandeep@techaddict.me>

Closes #12977 from techaddict/SPARK-15178.

[SPARK-15134][EXAMPLE] Indent SparkSession builder patterns and update binary_classification_metrics_example.py

## What changes were proposed in this pull request?

This issue addresses the comments in SPARK-15031 and also fix java-linter errors.
- Use multiline format in SparkSession builder patterns.
- Update `binary_classification_metrics_example.py` to use `SparkSession`.
- Fix Java Linter errors (in SPARK-13745, SPARK-15031, and so far)

## How was this patch tested?

After passing the Jenkins tests and run `dev/lint-java` manually.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #12911 from dongjoon-hyun/SPARK-15134.

## What changes were proposed in this pull request?

Add more informative logging in the external shuffle service to aid in debugging who is connecting to the YARN Nodemanager when the external shuffle service runs under it.

## How was this patch tested?

Ran and saw logs coming out in log file.

Author: Thomas Graves <tgraves@staydecay.corp.gq1.yahoo.com>

Closes #12900 from tgravescs/SPARK-15121.

This reverts commit dae538a4.

## What changes were proposed in this pull request?

This PR adds `since` tag into the matrix and vector classes in spark-mllib-local.

## How was this patch tested?

Scala-style checks passed.

Author: Pravin Gadakh <prgadakh@in.ibm.com>

Closes #12416 from pravingadakh/SPARK-14613.