[SPARK-4404]SparkSubmitDriverBootstrapper should stop after its SparkSubmit sub-proc...

[WangTaoTheTonic]

...ess ends

https://issues.apache.org/jira/browse/SPARK-4404

When we have spark.driver.extra* or spark.driver.memory in SPARK_SUBMIT_PROPERTIES_FILE, spark-class will use SparkSubmitDriverBootstrapper to launch driver.
If we get process id of SparkSubmitDriverBootstrapper and wanna kill it during its running, we expect its SparkSubmit sub-process stop also.

[SparkQA]

Test build #23371 has started for PR 3266 at commit 57b5ca1.

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[SparkQA]

Test build #23371 has finished for PR 3266 at commit 57b5ca1.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

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[andrewor14]

No need to name this thread. Also, could you add a comment here to explain that this is for killing the app while it's running? Otherwise it's not clear to me why we need to do this here and do the same at the end of the file again.

[andrewor14]

Hey @WangTaoTheTonic small comment but LGTM.

[WangTaoTheTonic]

@andrewor14 Done. Thanks for you review.

[SparkQA]

Test build #23405 has started for PR 3266 at commit e03eba5.

• This patch merges cleanly.

[SparkQA]

Test build #23405 has finished for PR 3266 at commit e03eba5.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/23405/
Test PASSed.

[andrewor14]

Ok I merge 1.2 master