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https://issues.apache.org/jira/browse/HIVE-16484?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16317318#comment-16317318
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Marcelo Vanzin commented on HIVE-16484:
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Just amending my previous response: if the concern with {{SparkLauncher}} is
the number of file descriptors because of the extra one used by the launcher
server connection, using {{InProcessLauncher}} will probably end up decreasing
the number of fds being used. Instead of potentially 3 fds for a child process
(pipes for stdin / stdout / stderr), you have one for the socket connection.
For the normal, child process case, then yes, you just get one extra file
descriptor. (Or maybe you get even, because I think {{SparkLauncher}} will
merge stdout and stderr in that case.)
As for why this is better, I think the main advantage will come by using
{{InProcessLauncher}} eventually, since Hive wouldn't need a separate Spark
installation to be able to launch Spark apps. It could ship with everything
ready to run HoS out of the box.
Security can probably become simpler; instead of having to run kinit before
starting a Spark child process, HS2 could potentially just instantiate
{{InProcessLauncher}} inside a {{proxyUser.doAs}} call. I haven't actually
tried that, but that's the general idea of how to use it in a secure env.
> Investigate SparkLauncher for HoS as alternative to bin/spark-submit
> --------------------------------------------------------------------
>
> Key: HIVE-16484
> URL: https://issues.apache.org/jira/browse/HIVE-16484
> Project: Hive
> Issue Type: Bug
> Components: Spark
> Reporter: Sahil Takiar
> Assignee: Sahil Takiar
> Attachments: HIVE-16484.1.patch, HIVE-16484.10.patch,
> HIVE-16484.2.patch, HIVE-16484.3.patch, HIVE-16484.4.patch,
> HIVE-16484.5.patch, HIVE-16484.6.patch, HIVE-16484.7.patch,
> HIVE-16484.8.patch, HIVE-16484.9.patch
>
>
> The {{SparkClientImpl#startDriver}} currently looks for the {{SPARK_HOME}}
> directory and invokes the {{bin/spark-submit}} script, which spawns a
> separate process to run the Spark application.
> {{SparkLauncher}} was added in SPARK-4924 and is a programatic way to launch
> Spark applications.
> I see a few advantages:
> * No need to spawn a separate process to launch a HoS --> lower startup time
> * Simplifies the code in {{SparkClientImpl}} --> easier to debug
> * {{SparkLauncher#startApplication}} returns a {{SparkAppHandle}} which
> contains some useful utilities for querying the state of the Spark job
> ** It also allows the launcher to specify a list of job listeners
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