[jira] [Commented] (IMPALA-9706) Test that queries are not retried if they cause an impalad to crash

["Tim Armstrong (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IMPALA-9706?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17132726#comment-17132726 ] 

Tim Armstrong commented on IMPALA-9706:
---------------------------------------

I had thought about this at one point with a group and I think it's basically hard.

Often we know a thread belongs to a query (or is executing an operation on behalf of a query) cause we store that in a thread-local variable. That can't be 100% accurate for various reasons, but would probably be accurate 95% of the time.

The problem then is actually communicating that the particular query caused the crash in a timely manner (the process is crashing obviously, so can't really do very much safely). The least crazy idea I heard is to have the crashing process write the offending query ID to a file (or stdout, or somewhere else) and have a watchdog process that broadcasts the fact that the query caused a crash to whoever needs to know.

That is a fair bit of complexity though.



> Test that queries are not retried if they cause an impalad to crash
> -------------------------------------------------------------------
>
>                 Key: IMPALA-9706
>                 URL: https://issues.apache.org/jira/browse/IMPALA-9706
>             Project: IMPALA
>          Issue Type: Sub-task
>          Components: Backend
>            Reporter: Sahil Takiar
>            Priority: Major
>
> IMPALA-9199 adds the core functionality for retrying queries, but it does not contain any tests that validate a query is not retried if the query itself caused an impalad to crash. If a query causes an impalad to crash, it should not be retried because it will likely just cause the impalad to crash again.
> There may not be a straightforward way to do this. I'm not sure how Impala can differentiate between query "x" causing a crash vs. anything else that can cause an impalad to crash. However, opening this JIRA to (1) document that this could be an issue, and (2) brainstorm any ideas.



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