[SPARK-22154] add a shutdown hook that explains why the output is terminating

[liu-zhaokun]

It would be nice to add a shutdown hook here that explains why the output is terminating. Otherwise if the worker dies the executor logs will silently stop.

[srowen]

The events of a shutdown are already logged; what does this add? it's already clear something is shutting down

[AmplabJenkins]

Can one of the admins verify this patch?

[liu-zhaokun]

It says that "It would be nice to add a shutdown hook here that explains why the output is terminating. Otherwise if the worker dies the executor logs will silently stop" in "TODO",I think it is justified.

[srowen]

Why a shutdown hook instead of something in the lifecycle of this process?

[liu-zhaokun]

@srowen
Sorry,I do not understand what you mean，could you explain it again?

[srowen]

Where does the worker exit normally or in case of an error? Why not log there?

[liu-zhaokun]

@srowen
This hook is only for DriverRunner.I think there was some log like this for normal executor when worker shutdown.

[jiangxb1987]

I'm going to close this PR because it goes stale, please feel free to reopen it or open another PR if anyone have more thoughts on this issue.