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https://issues.apache.org/jira/browse/HIVE-12170?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14960970#comment-14960970
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Alan Gates commented on HIVE-12170:
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bq. if the semantics are that we setConf once and then always use it, should it
detect cases when setConf is called with different conf and fail?
Probably, but I was worried about the cost of comparing configs. I was also
wondering if there was a single place we could set it so that any subsequent
call to setConf was an error, but I couldn't think of such a place.
> normalize HBase metastore connection configuration
> --------------------------------------------------
>
> Key: HIVE-12170
> URL: https://issues.apache.org/jira/browse/HIVE-12170
> Project: Hive
> Issue Type: Bug
> Reporter: Sergey Shelukhin
> Priority: Blocker
> Fix For: 2.0.0
>
> Attachments: HIVE-12170.patch
>
>
> Right now there are two ways to get HBaseReadWrite instance in metastore.
> Both get a threadlocal instance (is there a good reason for that?).
> 1) One is w/o conf and only works if someone called the (2) before, from any
> thread.
> 2) The other blindly sets a static conf and then gets an instance with that
> conf, or if someone already happened to call (1) or (2) from this thread, it
> returns the existing instance with whatever conf was set before (but still
> resets the current conf to new conf).
> This doesn't make sense even in an already-thread-safe case (like linear
> CLI-based tests), and can easily lead to bugs as described; the config
> propagation logic is not good (example - HIVE-12167); some calls just reset
> config blindly, so there's no point in setting staticConf, other than for the
> callers of method (1) above who don't have a conf and would rely on the
> static (which is bad design).
> Having connections with different configs reliably in not possible, and
> multi-threaded cases would also break - you could even set conf, have it
> reset and get instance with somebody else's conf.
> Static should definitely be removed, maybe threadlocal too (HConnection is
> thread-safe).
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