Tim Armstrong resolved IMPALA-4257.
    Resolution: Cannot Reproduce

> Parallel Queries fired from Cognos get stuck forever.
> -----------------------------------------------------
>                 Key: IMPALA-4257
>                 URL: https://issues.apache.org/jira/browse/IMPALA-4257
>             Project: IMPALA
>          Issue Type: Bug
>          Components: Clients
>    Affects Versions: Impala 2.5.0
>         Environment: Dev
>            Reporter: Deepak Nagar
>            Priority: Major
>              Labels: performance
>         Attachments: profile (1).txt, profile (2).txt, profile (3).txt, 
> profile (4).txt, profile (5).txt, profile (6).txt, profile (7).txt, profile 
> (7).txt
> We are using cloudera Impala 2.5.0 and created Parquet table (snappy 
> compression). These tables are being accessed by Cognos 10.2 version for 
> generating the reports and cognos 10.2 runs the queries in Dynamic Query Mode 
> (Dynamic Query Mode introduces the concept of a memory-resident data cache in 
> cognos. The query engine ultimately issue SQL code against the database in 
> order to populate the cache, only minimal and simplified queries are issued 
> against the database). These simplified queries are however fired to Impala 
> in parallel.
> The parallel execution of these queries seems to slowing down the whole 
> process and most of the queries (6 out of 8 fired in parallel in our case) 
> never finish, they run for days. The same set of queries when run 
> individually in sequence take only few seonds to complete.

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