[SPARK-4097] Fix the race condition of 'thread'

There is a chance that `thread` is null when calling `thread.interrupt()`.

```Scala
  override def cancel(): Unit = this.synchronized {
    _cancelled = true
    if (thread != null) {
      thread.interrupt()
    }
  }
```
Should put `thread = null` into a `synchronized` block to fix the race condition.

Author: zsxwing <zsxwing@gmail.com>

Closes #2957 from zsxwing/SPARK-4097 and squashes the following commits:

edf0aee [zsxwing] Add comments to explain the lock
c5cfeca [zsxwing] Fix the race condition of 'thread'
[SPARK-3795] Heuristics for dynamically scaling executors

This is part of a bigger effort to provide elastic scaling of executors within a Spark application ([SPARK-3174](https://issues.apache.org/jira/browse/SPARK-3174)). This PR does not provide any functionality by itself; it is a skeleton that is missing a mechanism to be added later in [SPARK-3822](https://issues.apache.org/jira/browse/SPARK-3822).

Comments and feedback are most welcome. For those of you reviewing this in detail, I highly recommend doing it through your favorite IDE instead of through the diff here.

Author: Andrew Or <andrewor14@gmail.com>
Author: Andrew Or <andrew@databricks.com>

Closes #2746 from andrewor14/scaling-heuristics and squashes the following commits:

8a4fdaa [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
e045df8 [Andrew Or] Add warning message (minor)
dfa31ec [Andrew Or] Fix tests
c0becc4 [Andrew Or] Merging with SPARK-3822
4784f93 [Andrew Or] Reword an awkward log message
181f27f [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
c79e907 [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
4672b90 [Andrew Or] It's nano time.
a6a30f2 [Andrew Or] Do not allow min/max executors of 0
c60ec33 [Andrew Or] Rewrite test logic with clocks
b00b680 [Andrew Or] Fix style
c3caa65 [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
7f9da14 [Andrew Or] Factor out logic to verify bounds on # executors (minor)
f279019 [Andrew Or] Add time mocking tests for polling loop
685e347 [Andrew Or] Factor out clock in polling loop to facilitate testing
3cea7f7 [Andrew Or] Use PrivateMethodTester to keep original class private
3156d81 [Andrew Or] Update comments and exception messages
92f36f9 [Andrew Or] Address minor review comments
abdea61 [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
2aefd09 [Andrew Or] Correct listener behavior
9fe6e44 [Andrew Or] Rename variables and configs + update comments and log messages
149cc32 [Andrew Or] Fix style
254c958 [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
5ff829b [Andrew Or] Add tests for ExecutorAllocationManager
19c6c4b [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
5896515 [Andrew Or] Move ExecutorAllocationManager out of scheduler package
9ca8945 [Andrew Or] Rewrite callbacks through the listener interface
5e336b9 [Andrew Or] Remove code from backend to avoid conflict with SPARK-3822
092d1fd [Andrew Or] Remove timeout logic for pending requests
1309fab [Andrew Or] Request executors by specifying the number pending
8bc0e9d [Andrew Or] Add logic to expire pending requests after timeouts
b750ee1 [Andrew Or] Express timers in terms of expiration times + remove retry logic
7f8dd47 [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
9d516cc [Andrew Or] Bug fix: Actually trigger the add timer / add retry timer
44f1832 [Andrew Or] Rename configs to include time units
eaae7ef [Andrew Or] Address various review comments
6f8be6c [Andrew Or] Beef up comments on what each of the timers mean
baaa403 [Andrew Or] Simplify variable names (minor)
42beec8 [Andrew Or] Reset whether the add threshold is crossed on cancellation
9bcc0bc [Andrew Or] ExecutorScalingManager -> ExecutorAllocationManager
2784398 [Andrew Or] Merge branch 'master' of github.com:apache/spark into scaling-heuristics
5a97d9e [Andrew Or] Log retry attempts in INFO + clean up logging
2f55c9f [Andrew Or] Do not keep requesting executors even after max attempts
0acd1cb [Andrew Or] Rewrite timer logic with polling
b3c7d44 [Andrew Or] Start the retry timer for adding executors at the right time
9b5f2ea [Andrew Or] Wording changes in comments and log messages
c2203a5 [Andrew Or] Simplify code to access the scheduler backend
e519d08 [Andrew Or] Simplify initialization code
2cc87a7 [Andrew Or] Add retry logic for removing executors
d0b34a6 [Andrew Or] Add retry logic for adding executors
9cc4649 [Andrew Or] Simplifying synchronization logic
67c03c7 [Andrew Or] Correct semantics of adding executors + update comments
6c48ab0 [Andrew Or] Update synchronization comment
8901900 [Andrew Or] Simplify remove policy + change the semantics of add policy
1cc8444 [Andrew Or] Minor wording change
ae5b64a [Andrew Or] Add synchronization
20ec6b9 [Andrew Or] First cut implementation of removing executors dynamically
4077ae2 [Andrew Or] Minor code re-organization
6f1fa66 [Andrew Or] First cut implementation of adding executors dynamically
b2e6dcc [Andrew Or] Add skeleton interface for requesting / killing executors
[SPARK-4053][Streaming] Made the ReceiverSuite test more reliable, by fixing block generator throttling

In the unit test that checked whether blocks generated by throttled block generator had expected number of records, the thresholds are too tight, which sometimes led to the test failing.
This PR fixes it by relaxing the thresholds and the time intervals for testing.

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

Closes #2900 from tdas/receiver-suite-flakiness and squashes the following commits:

28508a2 [Tathagata Das] Made the ReceiverSuite test more reliable
[SPARK-1720][SPARK-1719] use LD_LIBRARY_PATH instead of -Djava.library.path

- [X] Standalone
- [X] YARN
- [X] Mesos
- [X]  Mac OS X
- [X] Linux
- [ ]  Windows

This is another implementation about #1031

Author: GuoQiang Li <witgo@qq.com>

Closes #2711 from witgo/SPARK-1719 and squashes the following commits:

c7b26f6 [GuoQiang Li] review commits
4488e41 [GuoQiang Li] Refactoring CommandUtils
a444094 [GuoQiang Li] review commits
40c0b4a [GuoQiang Li] Add buildLocalCommand method
c1a0ddd [GuoQiang Li] fix comments
156ce88 [GuoQiang Li] review commit
38aa377 [GuoQiang Li] Refactor CommandUtils.scala
4269e00 [GuoQiang Li] Refactor SparkSubmitDriverBootstrapper.scala
7a1d634 [GuoQiang Li] use LD_LIBRARY_PATH instead of -Djava.library.path
[SPARK-4102] Remove unused ShuffleReader.stop() method.

This method is not implemented by the only subclass
(HashShuffleReader), nor is it ever called. While the
use of Scala's fancy "???" was pretty exciting, the method's
existence can only lead to confusion and it therefore should
be deleted.

mateiz was there a reason for adding this that I'm
missing?

Author: Kay Ousterhout <kayousterhout@gmail.com>

Closes #2966 from kayousterhout/SPARK-4102 and squashes the following commits:

532c564 [Kay Ousterhout] Added back commented-out method, as per Matei's request
904655e [Kay Ousterhout] [SPARK-4102] Remove unused ShuffleReader.stop() method.
[SPARK-4130][MLlib] Fixing libSVM parser bug with extra whitespace

This simple patch filters out extra whitespace entries.

Author: Joseph E. Gonzalez <joseph.e.gonzalez@gmail.com>
Author: Joey <joseph.e.gonzalez@gmail.com>

Closes #2996 from jegonzal/loadLibSVM and squashes the following commits:

e0227ab [Joey] improving readability
e028e84 [Joseph E. Gonzalez] fixing whitespace bug in loadLibSVMFile when parsing libSVM files
SPARK-4111 [MLlib] add regression metrics

Add RegressionMetrics.scala as regression metrics used for evaluation and corresponding test case RegressionMetricsSuite.scala.

Author: Yanbo Liang <yanbohappy@gmail.com>
Author: liangyanbo <liangyanbo@meituan.com>

Closes #2978 from yanbohappy/regression_metrics and squashes the following commits:

730d0a9 [Yanbo Liang] more clearly annotation
3d0bec1 [Yanbo Liang] rename and keep code style
a8ad3e3 [Yanbo Liang] simplify code for keeping style
d454909 [Yanbo Liang] rename parameter and function names, delete unused columns, add reference
2e56282 [liangyanbo] rename r2_score() and remove unused column
43bb12b [liangyanbo] add regression metrics
[SPARK-4028][Streaming] ReceivedBlockHandler interface to abstract the functionality of storage of received data

As part of the initiative to prevent data loss on streaming driver failure, this JIRA tracks the subtask of implementing a ReceivedBlockHandler, that abstracts the functionality of storage of received data blocks. The default implementation will maintain the current behavior of storing the data into BlockManager. The optional implementation will store the data to both BlockManager as well as a write ahead log.

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

Closes #2940 from tdas/driver-ha-rbh and squashes the following commits:

78a4aaa [Tathagata Das] Fixed bug causing test failures.
f192f47 [Tathagata Das] Fixed import order.
df5f320 [Tathagata Das] Updated code to use ReceivedBlockStoreResult as the return type for handler's storeBlock
33c30c9 [Tathagata Das] Added license, and organized imports.
2f025b3 [Tathagata Das] Updates based on PR comments.
18aec1e [Tathagata Das] Moved ReceivedBlockInfo back into spark.streaming.scheduler package
95a4987 [Tathagata Das] Added ReceivedBlockHandler and its associated tests
[SPARK-4027][Streaming] WriteAheadLogBackedBlockRDD to read received either from BlockManager or WAL in HDFS

As part of the initiative of preventing data loss on streaming driver failure, this sub-task implements a BlockRDD that is backed by HDFS. This BlockRDD can either read data from the Spark's BlockManager, or read the data from file-segments in write ahead log in HDFS.

Most of this code has been written by @harishreedharan

Author: Tathagata Das <tathagata.das1565@gmail.com>
Author: Hari Shreedharan <hshreedharan@apache.org>

Closes #2931 from tdas/driver-ha-rdd and squashes the following commits:

209e49c [Tathagata Das] Better fix to style issue.
4a5866f [Tathagata Das] Addressed one more comment.
ed5fbf0 [Tathagata Das] Minor updates.
b0a18b1 [Tathagata Das] Fixed import order.
20aa7c6 [Tathagata Das] Fixed more line length issues.
29aa099 [Tathagata Das] Fixed line length issues.
9e47b5b [Tathagata Das] Renamed class, simplified+added unit tests.
6e1bfb8 [Tathagata Das] Tweaks testuite to create spark contxt lazily to prevent contxt leaks.
9c86a61 [Tathagata Das] Merge pull request #22 from harishreedharan/driver-ha-rdd
2878c38 [Hari Shreedharan] Shutdown spark context after tests. Formatting/minor fixes
c709f2f [Tathagata Das] Merge pull request #21 from harishreedharan/driver-ha-rdd
5cce16f [Hari Shreedharan] Make sure getBlockLocations uses offset and length to find the blocks on HDFS
eadde56 [Tathagata Das] Transferred HDFSBackedBlockRDD for the driver-ha-working branch
[SPARK-4078] New FsPermission instance w/o FsPermission.createImmutable in eventlog

By default, Spark builds its package against Hadoop 1.0.4 version. In that version, it has some FsPermission bug (see [HADOOP-7629] (https://issues.apache.org/jira/browse/HADOOP-7629) by Todd Lipcon). This bug got fixed since 1.1 version. By using that FsPermission.createImmutable() API, end-user may see some RPC exception like below (if turn on eventlog over HDFS).  Here proposes a quick fix to avoid certain exception for all hadoop versions.
```
Exception in thread "main" java.io.IOException: Call to sr484/10.1.2.84:54310 failed on local exception: java.io.EOFException
        at org.apache.hadoop.ipc.Client.wrapException(Client.java:1150)
        at org.apache.hadoop.ipc.Client.call(Client.java:1118)
        at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:229)
        at $Proxy6.setPermission(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:85)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:62)
        at $Proxy6.setPermission(Unknown Source)
        at org.apache.hadoop.hdfs.DFSClient.setPermission(DFSClient.java:1285)
        at org.apache.hadoop.hdfs.DistributedFileSystem.setPermission(DistributedFileSystem.java:572)
        at org.apache.spark.util.FileLogger.createLogDir(FileLogger.scala:138)
        at org.apache.spark.util.FileLogger.start(FileLogger.scala:115)
        at org.apache.spark.scheduler.EventLoggingListener.start(EventLoggingListener.scala:74)
        at org.apache.spark.SparkContext.<init>(SparkContext.scala:324)
```

Author: Grace <jie.huang@intel.com>

Closes #2892 from GraceH/eventlog-rpc and squashes the following commits:

58ea038 [Grace] new FsPermission Instance w/o FsPermission.createImmutable
[SPARK-3319] [SPARK-3338] Resolve Spark submit config paths

The bulk of this PR is comprised of tests. All changes in functionality are made in `SparkSubmit.scala` (~20 lines).

**SPARK-3319.** There is currently a divergence in behavior when the user passes in additional jars through `--jars` and through setting `spark.jars` in the default properties file. The former will happily resolve the paths (e.g. convert `my.jar` to `file:/absolute/path/to/my.jar`), while the latter does not. We should resolve paths consistently in both cases. This also applies to the following pairs of command line arguments and Spark configs:

- `--jars` ~ `spark.jars`
- `--files` ~ `spark.files` / `spark.yarn.dist.files`
- `--archives` ~ `spark.yarn.dist.archives`
- `--py-files` ~ `spark.submit.pyFiles`

**SPARK-3338.** This PR also fixes the following bug: if the user sets `spark.submit.pyFiles` in his/her properties file, it does not actually get picked up even if `--py-files` is not set. This is simply because the config is overridden by an empty string.

Author: Andrew Or <andrewor14@gmail.com>
Author: Andrew Or <andrew@databricks.com>

Closes #2232 from andrewor14/resolve-config-paths and squashes the following commits:

fff2869 [Andrew Or] Add spark.yarn.jar
da3a1c1 [Andrew Or] Merge branch 'master' of github.com:apache/spark into resolve-config-paths
f0fae64 [Andrew Or] Merge branch 'master' of github.com:apache/spark into resolve-config-paths
05e03d6 [Andrew Or] Add tests for resolving both command line and config paths
460117e [Andrew Or] Resolve config paths properly
fe039d3 [Andrew Or] Beef up tests to test fixed-pointed-ness of Utils.resolveURI(s)
[SPARK-4138][SPARK-4139] Improve dynamic allocation settings

This should be merged after #2746 (SPARK-3795).

**SPARK-4138**. If the user sets both the number of executors and `spark.dynamicAllocation.enabled`, we should throw an exception.

**SPARK-4139**. If the user sets `spark.dynamicAllocation.enabled`, we should use the max number of executors as the starting number of executors because the first job is likely to run immediately after application startup. If the latter is not set, throw an exception.

Author: Andrew Or <andrew@databricks.com>

Closes #3002 from andrewor14/yarn-set-executors and squashes the following commits:

c528fce [Andrew Or] Merge branch 'master' of github.com:apache/spark into yarn-set-executors
55d4699 [Andrew Or] Bug fix: `isDynamicAllocationEnabled` was always false
2b0ccec [Andrew Or] Start the number of executors at the max
022bfde [Andrew Or] Guard against incompatible settings of number of executors
[Minor] A few typos in comments and log messages

Author: Andrew Or <andrewor14@gmail.com>
Author: Andrew Or <andrew@databricks.com>

Closes #3021 from andrewor14/typos and squashes the following commits:

daaf417 [Andrew Or] Merge branch 'master' of github.com:apache/spark into typos
4838ae4 [Andrew Or] Merge branch 'master' of github.com:apache/spark into typos
026d426 [Andrew Or] Merge branch 'master' of github.com:andrewor14/spark into typos
a81ae8f [Andrew Or] Some typos
[SPARK-4155] Consolidate usages of <driver>

We use "\<driver\>" everywhere. Let's not do that.

Author: Andrew Or <andrew@databricks.com>

Closes #3020 from andrewor14/consolidate-driver and squashes the following commits:

c1c2204 [Andrew Or] Just use "<driver>" for local executor ID
3d751e9 [Andrew Or] Consolidate usages of <driver>
Minor style hot fix after #2711

I had planned to fix this when I merged it but I forgot to. witgo

Author: Andrew Or <andrew@databricks.com>

Closes #3018 from andrewor14/command-utils-style and squashes the following commits:

c2959fb [Andrew Or] Style hot fix
[SPARK-4153][WebUI] Update the sort keys for HistoryPage

Sort "Started", "Completed", "Duration" and "Last Updated" by time.

Author: zsxwing <zsxwing@gmail.com>

Closes #3014 from zsxwing/SPARK-4153 and squashes the following commits:

ec8b9ad [zsxwing] Sort "Started", "Completed", "Duration" and "Last Updated" by time
[SPARK-3661] Respect spark.*.memory in cluster mode

This also includes minor re-organization of the code. Tested locally in both client and deploy modes.

Author: Andrew Or <andrew@databricks.com>
Author: Andrew Or <andrewor14@gmail.com>

Closes #2697 from andrewor14/memory-cluster-mode and squashes the following commits:

01d78bc [Andrew Or] Merge branch 'master' of github.com:apache/spark into memory-cluster-mode
ccd468b [Andrew Or] Add some comments per Patrick
c956577 [Andrew Or] Tweak wording
2b4afa0 [Andrew Or] Unused import
47a5a88 [Andrew Or] Correct Spark properties precedence order
bf64717 [Andrew Or] Merge branch 'master' of github.com:apache/spark into memory-cluster-mode
dd452d0 [Andrew Or] Respect spark.*.memory in cluster mode
SPARK-1209 [CORE] SparkHadoop{MapRed,MapReduce}Util should not use package org.apache.hadoop

(This is just a look at what completely moving the classes would look like. I know Patrick flagged that as maybe not OK, although, it's private?)

Author: Sean Owen <sowen@cloudera.com>

Closes #2814 from srowen/SPARK-1209 and squashes the following commits:

ead1115 [Sean Owen] Disable MIMA warnings resulting from moving the class -- this was also part of the PairRDDFunctions type hierarchy though?
2d42c1d [Sean Owen] Move SparkHadoopMapRedUtil / SparkHadoopMapReduceUtil from org.apache.hadoop to org.apache.spark
[SPARK-4120][SQL] Join of multiple tables with syntax like SELECT .. FROM T1,T2,T3.. does not work in SparkSQL

Right now it works for only 2 tables like below query.
sql("SELECT * FROM records1 as a,records2 as b where a.key=b.key ")

But it does not work for more than 2 tables like below query
sql("SELECT * FROM records1 as a,records2 as b,records3 as c where a.key=b.key and a.key=c.key").

Author: ravipesala <ravindra.pesala@huawei.com>

Closes #2987 from ravipesala/multijoin and squashes the following commits:

429b005 [ravipesala] Support multiple joins
[SPARK-3968][SQL] Use parquet-mr filter2 api

The parquet-mr project has introduced a new filter api  (https://github.com/apache/incubator-parquet-mr/pull/4), along with several fixes . It can also eliminate entire RowGroups depending on certain statistics like min/max
We can leverage that to further improve performance of queries with filters.
Also filter2 api introduces ability to create custom filters. We can create a custom filter for the optimized In clause (InSet) , so that elimination happens in the ParquetRecordReader itself

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

Closes #2841 from saucam/master and squashes the following commits:

8282ba0 [Yash Datta] SPARK-3968: fix scala code style and add some more tests for filtering on optional columns
515df1c [Yash Datta] SPARK-3968: Add a test case for filter pushdown on optional column
5f4530e [Yash Datta] SPARK-3968: Fix scala code style
f304667 [Yash Datta] SPARK-3968: Using task metadata strategy for row group filtering
ec53e92 [Yash Datta] SPARK-3968: No push down should result in case we are unable to create a record filter
48163c3 [Yash Datta] SPARK-3968: Code cleanup
cc7b596 [Yash Datta] SPARK-3968: 1. Fix RowGroupFiltering not working             2. Use the serialization/deserialization from Parquet library for filter pushdown
caed851 [Yash Datta] Revert "SPARK-3968: Not pushing the filters in case of OPTIONAL columns" since filtering on optional columns is now supported in filter2 api
49703c9 [Yash Datta] SPARK-3968: Not pushing the filters in case of OPTIONAL columns
9d09741 [Yash Datta] SPARK-3968: Change parquet filter pushdown to use filter2 api of parquet-mr