## What changes were proposed in this pull request?

Users might want to start multiple mesos dispatchers, as each dispatcher can potentially be part of different roles and used for multi-tenancy.

To allow multiple Mesos dispatchers to be launched, we need to be able to specify a instance number when starting the dispatcher daemon.

## How was the this patch tested?

Manual testing

Author: Timothy Chen <tnachen@gmail.com>

Closes #11281 from tnachen/multiple_cluster_dispatchers.

This PR is based on the work of roji to support running Spark scripts from symlinks. Thanks for the great work roji . Would you mind taking a look at this PR, thanks a lot.

For releases like HDP and others, normally it will expose the Spark executables as symlinks and put in `PATH`, but current Spark's scripts do not support finding real path from symlink recursively, this will make spark fail to execute from symlink. This PR try to solve this issue by finding the absolute path from symlink.

Instead of using `readlink -f` like what this PR (https://github.com/apache/spark/pull/2386) implemented is that `-f` is not support for Mac, so here manually seeking the path through loop.

I've tested with Mac and Linux (Cent OS), looks fine.

This PR did not fix the scripts under `sbin` folder, not sure if it needs to be fixed also?

Please help to review, any comment is greatly appreciated.

Author: jerryshao <sshao@hortonworks.com>
Author: Shay Rojansky <roji@roji.org>

Closes #8669 from jerryshao/SPARK-2960.

This patch adds the support for cluster mode to run on Mesos.
It introduces a new Mesos framework dedicated to launch new apps/drivers, and can be called with the spark-submit script and specifying --master flag to the cluster mode REST interface instead of Mesos master.

Example:
./bin/spark-submit --deploy-mode cluster --class org.apache.spark.examples.SparkPi --master mesos://10.0.0.206:8077 --executor-memory 1G --total-executor-cores 100 examples/target/spark-examples_2.10-1.3.0-SNAPSHOT.jar 30

Part of this patch is also to abstract the StandaloneRestServer so it can have different implementations of the REST endpoints.

Features of the cluster mode in this PR:
- Supports supervise mode where scheduler will keep trying to reschedule exited job.
- Adds a new UI for the cluster mode scheduler to see all the running jobs, finished jobs, and supervise jobs waiting to be retried
- Supports state persistence to ZK, so when the cluster scheduler fails over it can pick up all the queued and running jobs

Author: Timothy Chen <tnachen@gmail.com>
Author: Luc Bourlier <luc.bourlier@typesafe.com>

Closes #5144 from tnachen/mesos_cluster_mode and squashes the following commits:

069e946 [Timothy Chen] Fix rebase.
e24b512 [Timothy Chen] Persist submitted driver.
390c491 [Timothy Chen] Fix zk conf key for mesos zk engine.
e324ac1 [Timothy Chen] Fix merge.
fd5259d [Timothy Chen] Address review comments.
1553230 [Timothy Chen] Address review comments.
c6c6b73 [Timothy Chen] Pass spark properties to mesos cluster tasks.
f7d8046 [Timothy Chen] Change app name to spark cluster.
17f93a2 [Timothy Chen] Fix head of line blocking in scheduling drivers.
6ff8e5c [Timothy Chen] Address comments and add logging.
df355cd [Timothy Chen] Add metrics to mesos cluster scheduler.
20f7284 [Timothy Chen] Address review comments
7252612 [Timothy Chen] Fix tests.
a46ad66 [Timothy Chen] Allow zk cli param override.
920fc4b [Timothy Chen] Fix scala style issues.
862b5b5 [Timothy Chen] Support asking driver status when it's retrying.
7f214c2 [Timothy Chen] Fix RetryState visibility
e0f33f7 [Timothy Chen] Add supervise support and persist retries.
371ce65 [Timothy Chen] Handle cluster mode recovery and state persistence.
3d4dfa1 [Luc Bourlier] Adds support to kill submissions
febfaba [Timothy Chen] Bound the finished drivers in memory
543a98d [Timothy Chen] Schedule multiple jobs
6887e5e [Timothy Chen] Support looking at SPARK_EXECUTOR_URI env variable in schedulers
8ec76bc [Timothy Chen] Fix Mesos dispatcher UI.
d57d77d [Timothy Chen] Add documentation
825afa0 [Luc Bourlier] Supports more spark-submit parameters
b8e7181 [Luc Bourlier] Adds a shutdown latch to keep the deamon running
0fa7780 [Luc Bourlier] Launch task through the mesos scheduler
5b7a12b [Timothy Chen] WIP: Making a cluster mode a mesos framework.
4b2f5ef [Timothy Chen] Specify user jar in command to be replaced with local.
e775001 [Timothy Chen] Support fetching remote uris in driver runner.
7179495 [Timothy Chen] Change Driver page output and add logging
880bc27 [Timothy Chen] Add Mesos Cluster UI to display driver results
9986731 [Timothy Chen] Kill drivers when shutdown
67cbc18 [Timothy Chen] Rename StandaloneRestClient to RestClient and add sbin scripts
e3facdd [Timothy Chen] Add Mesos Cluster dispatcher

Found it by accident. I'm not gonna file jira for this as it is a very tiny fix.

Author: WangTaoTheTonic <wangtao111@huawei.com>

Closes #4936 from WangTaoTheTonic/wrongdesc and squashes the following commits:

fb8a8ec [WangTaoTheTonic] fix the wrong description
aca5596 [WangTaoTheTonic] fix the wrong description

This should all work as expected with the current version of the tachyon tarball (0.4.1)

Author: Nick Lanham <nick@afternight.org>

Closes #137 from nicklan/bundle-tachyon and squashes the following commits:

2eee15b [Nick Lanham] Put back in exec, start tachyon first
738ba23 [Nick Lanham] Move tachyon out of sbin
f2f9bc6 [Nick Lanham] More checks for tachyon script
111e8e1 [Nick Lanham] Only try tachyon operations if tachyon script exists
0561574 [Nick Lanham] Copy over web resources so web interface can run
4dc9809 [Nick Lanham] Update to tachyon 0.4.1
0a1a20c [Nick Lanham] Add scripts using tachyon tarball

Signed-off-by: shane-huang <shengsheng.huang@intel.com>

added SPARK_WORKER_INSTANCES : allows spawning multiple worker instances/processes on every slave machine

Heavily inspired by Hadoop cluster scripts ;-)